THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

LOS  ANGELES 


Cyclopedia 

•>f 

Civil  Engineering 


A  General  Reference  Work  on 


SURVEYING,  HIGHWAY  CONSTRUCTION,  RAILROAD   ENGINEERING,  EARTHWORK, 

STEEL  CONSTRUCTION,  SPECIFICATIONS,  CONTRACTS,  BRIDGE  ENGINEERING, 

MASONRY  AND    REINFORCED    CONCRETE,    MUNICIPAL   ENGINEERING, 

HYDRAULIC  ENGINEERING,  RIVER  AND  HARBOR  IMPROVEMENT, 

IRRIGATION   ENGINEERING,  COST  ANALYSIS,  ETC. 


Prepared  by  a  Corps  of 


CIVIL  AND   CONSULTING   ENGINEERS   AND   TECHNICAL   EXPERTS  OF  THE 
HIGHEST   PROFESSIONAL   STANDING 


Illustrated  with  over  Two  Thousand  Engravings 


NINE  VOLUMES 


CHICAGO 

AMERICAN  TECHNICAL  SOCIETY 
1916 


COPYRIGHT.  1908,  1909.  1915.  1916 

BY 

AMERICAN    TECHNICAL    SOCIETY 


COPYRIGHT.  1908.  1909,  1915.  1916 
BY 

AMERICAN    SCHOOL    OF    CORRESPONDENCE 

Copyrighted  in  Great  Britain 
All  Rights  Reserved 


Engineering 
Library 

TA 

145 


Authors    and    Collaborators 


FREDERICK  E.  TURNEAURE,  C.  E.,  Dr.  Eng. 

Dean  of  the  College  of  Engineering,    and   Professor  of  Engineering,  University  of 

Wisconsin 

Member,  American  Society  of  Civil  Engineers 
Joint  Author  of  "Principles  of  Reinforced  Concrete  Construction,"    "Public  Water 

Supplies,"  etc. 


FRANK  0.  DUFOUR,  C.  E. 

Structural  Engineer  with  Interstate  Commerce  Commission  Division  of    Valuation, 

Central  District 

Formerly  Assistant  Professor  of  Structural  Engineering,  University  of  Illinois 
Member,  American  Society  of  Civil  Engineers 
Member,  American  Society  for  Testing  Materials 


WALTER  LORING  WEBB,  C.  E. 

Consulting  Civil  Engineer 

Member,  American  Society  of  Civil  Engineers 

Author  of  "Railroad  Construction,"   "Economics  of  Railroad  Construction,"  etc. 


W.  G.  BLIGH 

Inspecting  Engineer  of  Irrigation  Works,  Department  of  Interior,  Canada 
Formerly  in  Engineering  Service  of  His  Majesty  in  India 
Member,  Institute  Civil  Engineers  (London) 
Member,  American  Society  of  Civil  Engineers 
Member,  Canadian  Society  of  Civil  Engineers 


ADOLPH  BLACK,  C.  E. 

Civil  and  Sanitary  Engineer,  General  Chemical  Company,  New  York  City 
Formerly  Adjunct  Professor  of  Civil  Engineering,  Columbia  University 


EDWARD  R.  MAURER,  B.  C.  E. 

Professor  of  Mechanics,  University  of  Wisconsin 

Joint  Author  of  "Principles  of  Reinforced  Concrete  Construction" 


AUSTIN  T.  BYRNE 

Civil  Engineer 

Author  of  "Highway  Construction,"  "Materials  and  Workmanship' 


Authors  and  Collaborators— Continued 


A.  MARSTON,  C.  E. 

Dean  of  Division  of  Engineering  and  Professor  of  Civil  Engineering,  Iowa  State  College 
Member.  American  Society  of  Civil  Engineers 
Member,  Western  Society  of  Civil  Engineers 


De  WITT  V.  MOORE 

Consulting  Engineer  and  Architect 

District  Engineer— Central  District  Division  of  Valuation 

Interstate  Commerce  Commission,  Chicago 

Member,  American  Society  Engineering  Contractors 

Member,  Indiana  Engineering  Society 


W.  HERBERT  GIBSON,  B.  S.,  C.  E. 

Civil  Engineer 

Designer  of  Reinforced  Concrete 


C.  D.  RAWSTORNE,  C.  E. 

Consulting  Engineer,  Civil  Engineering  Department,  American  School  of  Correspondence 
Formerly  Superintendent  of  Construction,  John  M,  Ewen  Company 


HENRY  J.  BURT,  B.  S.,  C.  E. 

Structural  Engineer  for  Holabird  and  Roche,  Architects 

Member,  American  Society  of  Civil  Engineers 

Member,  Western  Society  of  Civil  Engineers 

Member,  Society  for  the  Promotion  of  Engineering  Education 


RICHARD  I.  D.  ASHBRIDGE 

Civil  Engineer 

Member,  American  Society  of  Civil  Engineers 


HERMAN  K.  HIGGINS 

Civil  Engineer 

Associate  Member,  American  Society  of  Civil  Engineers 

Member,  Boston  Society  of  Civil  Engineers 

Member,  New  England  Water  Works  Association 

Member,  American  Railway  Bridge  and  Building  Association 


ALFRED  E,  PHILLIPS,  C.  E.,  Ph.  D. 

Professor  of  Civil  Engineering,  Armour  Institute  of  Technology 


Authors  and  Collaborators— Continued 


H.  E.  MURDOCK,  M.  E.,  C.  E. 

Head  of  Department  of  Agricultural  Engineering,  Montana  State  College,  Bozeman, 

Montana 
Formerly  Irrigation  Engineer,  U.  S.  Department  of  Agriculture 


A.  B.  McDANIEL,  B.  S. 

Assistant  Professor  of  Civil  Engineering,  University  of  Illinois 
Member,  American  Society  of  Civil  Engineers 
Member,  Society  for  the  Promotion  of  Engineering  Education 
Fellow,  Association  for  the  Advancement  of  Science 
Author  of  "Excavating  Machinery" 


GLENN  M.  HOBBS,  Ph.  D. 

Secretary  and  Educational  Director,  American  School  of  Correspondence 
Formerly  Instructor,  Department  of  Physics,  University  of  Chicago 
American  Physical  Society 


THOMAS  FLEMING,  Jr.,  B.  S.,  C.  E. 

With  Chester  &  Fleming,  Hydraulic  and  Sanitary  Engineers 
Associate  Member,  American  Society  of  Civil  Engineers 
Member,  New  England  Water  Works  Association 
Member,  Engineers'  Society  of  Pennsylvania 


CHARLES  E.  MORRISON,  C.  E. ,  Ph.  D. 

Formerly  Instructor  in  Civil  Engineering,  Columbia  University 

Associate  Member,  American  Society  of  Civil  Engineers 

Author  of  "Highway  Engineering",  "High  Masonry  Dam  Design" 


EDWARD  B.  WAITE 

Formerly  Dean,  and  Head,  Consulting  Department,  American  School  of  Correspondence 
American  Society  of  Mechanical  Engineers 
Boston  Society  of  Civil  Engineers 


HAROLD  W.  ROBBINS,  M.  E. 

Formerly  Instructor,  Lewis  Institute,  and  Armour  Institute,  Chicago 
Past  Secretary,  The  Aero  Club  of  Illinois 
Special  Writer  and  Technical  Investigator 


JESSIE  M.  SHEPHERD,  A.  B. 

Head,  Publication  Department,  American  Technical  Society 


Authorities  Consulted 


THE  editors  have  freely  consulted  the  standard  technical  literature  of 
America  and  Europe  in  the  preparation  of  these  volumes.    They  de- 
sire to  express  their  indebtedness,  particularly,   to  the  following 
eminent  authorities,  whose  well-known  treatises  should  be  in  the  library  of 
everyone  interested  in  Civil  Engineering. 

Grateful  acknowledgment  is  here  made  also  for  the  invaluable  co- 
operation of  the  foremost  Civil,  Structural,  Railroad,  Hydraulic,  and  Sanitary 
Engineers  and  Manufacturers  in  making  these  volumes  thoroughly  repre- 
sentative of  the  very  best  and  latest  practice  in  every  branch  of  the  broad 
field  of  Civil  Engineering. 


WILLIAM  G.  RAYMOND,  C.  E. 

Dean  of  the  School  of  Applied  Science  and  Professor  of  Civil  Engineering  in  the  State 

University  of  Iowa;  American  Society  of  Civil  Engineers 
Author  of  "A  Textbook  of  Plane  Surveying,"  "The  Elements  of  Railroad  Engineering" 


JOSEPH  P.  FRIZELL 

Hydraulic  Engineer  and  Water-Power  Expert;  American  Society  of  Civil  Engineers 
Author  of  "Water  Power,  the  Development  and  Application  of  the  Energy  of  Flowing 
Water" 


FREDERICK  E.  TURNEAURE,  C.  E.,  Dr.  Eng. 

Dean  of  the  College  of  Engineering  and  Professor  of    Engineering.   University  of 

Wisconsin 
Joint  Author  of  "Public  Water  Supplies,"  "Theory  and  Practice  of  Modern  Framed 

Structures,"  "Principles  of  Reinforced  Concrete  Construction" 

HENRY  N.  OGDEN,  C.  E. 

Professor  of  Sanitary  Engineering,  Cornell  University 
Author  of  "Sewer  Design" 

V 

DANIEL  CARHART,  C.  E. 

Emeritus  Professor  of  Civil  Engineering.  University  of  Pittsburgh 
Author  of  "Treatise  on  Plane  Surveying" 

V 

HALBERT  P.  GILLETTE 

Editor  of 'Engineering  and  Contracting;  American  Society  of  Civil  Engineers;  Formerly 
Chief  Engineer.  Washington  State  Railroad  Commission 

Handbook  of  Cost  Data  for  Contractors  and  Engineers" 

CHARLES  E.  GREENE,  A.  M.,  C.  E. 

Late  Professor  of  Civil  Engineering.  University  of  Michigan 

Trusses  and  Arches,  Graphic  Method,"  "Structural  Mechanics" 


Authorities  Consulted— Continued 


A.  PRESCOTT  FOLWELL 

Editor  of  Municipal  Journal  and  Engineer;  Formerly  Professor  of  Municipal  Engineer- 
ing, Lafayette  College 
Author  of  "Water  Supply  Engineering,"  "Sewerage" 


IRVING  P.  CHURCH,  C.  E. 

Professor  of  Applied  Mechanics  and  Hydraulics,  Cornell  University 
Author  of  "Mechanics  of  Engineering" 


PAUL  C.  NUGENT,  A.  M.,  C.  E. 

Professor  of  Civil  Engineering,  Syracuse  University 
Author  of  "Plane  Surveying" 


FRANK  W.  SKINNER,  C.  E. 

Consulting  Engineer;  Associate  Editor  of  The  Engineering  Record 
Author  of  "Types  and  Details  of  Bridge  Construction" 


HANBURY  BROWN,  K.  C.  M.  G. 

Member  of  the  Institution  of  Civil  Engineers 
Author  of  "Irrigation,  Its  Principles  and  Practice" 


SANFORD  E.  THOMPSON,  S.  B.,  C.  E. 

American  Society  of  Civil  Engineers 

Joint  Author  of  "A  Treatise  on  Concrete,  Plain  and  Reinforced" 


JOSEPH  KENDALL  FREITAG,  B.  S.,  C.  E. 

American  Society  of  Civil  Engineers 

Author  of  "Architectural  Engineering,"  "Fireproofing  of  Steel  Buildings,"  "Fire  Pre- 
vention and  Fire  Protection" 


AUSTIN  T.  BYRNE,  C.  E. 

Civil  Engineer 

Author  of  "Highway  Construction,"  "Inspection  of  Materials  and  Workmanship  Em- 
ployed in  Construction" 


JOHN  F.  HAYFORD,  C.  E. 

Expert  Computer  and  Geodesist,  U.  S.  Coast  and  Geodetic  Survey 
Author  of  "A  Textbook  of  Geodetic  Astronomy" 


WALTER  LORING  WEBB,  C.  E. 

Consulting  Civil  Engineer;  American  Society  of  Civil  Engineers 

Author  of  "Railroad  Construction  in  Theory  and  Practice,"  "Economics  of  Railroad 
Construction,"  etc. 


Authorities  Consulted— Continued 


EDWARD  R.  MAURER,  B.  C.  E. 

Professor  of  Mechanics,  University  of  Wisconsin 

Joint  Author  of  "Principles  of  Reinforced  Concrete  Construction" 


HERBERT  M.  WILSON,  C.  E. 

Geographer  and  Former  Irrigation  Engineer,  United  States  Geological  Survey;  American 

Society  of  Civil  Engineers 
Author  of  "Topographic  Surveying,"  "Irrigation  Engineering,"  etc. 


MANSFIELD  MERRIMAN,  C.  E.,  Ph.  D. 

Consulting  Engineer 

Formerly  Professer  of  Civil  Engineering.  Lehigh  University 

Author  of  "The  Elements  of  Precise  Surveying  and  Geodesy,"  "A  Treatise  on  Hy- 
draulics," "Mechanics  of  Materials,"  "Retaining  Walls  and  Masonry  Dams." 
"Introduction  to  Geodetic  Surveying,"  "A  Textbook  on  Roofs  and  Bridges,"  "A 
Handbook  for  Surveyors,"  "American  Civil  Engineers'  Pocket  Book" 


DAVID  M.  STAUFFER 

American  Society  of  Civil  Engineers;  Institution  of  Civil  Engineers;  Vice-President, 

Engineering  News  Publishing  Co. 
Author  of  "Modern  Tunnel  Practice" 


CHARLES  L.  CRANDALL 

Professor  of  Railroad  Engineering  and  Geodesy  in  Cornell  University 
Author  of  "A  Textbook  on  Geodesy  and  Least  Squares" 


N.  CLIFFORD  RICKER,  M.  Arch. 

Professor  of  Architecture,  University  of  Illinois;  Fellow  of  the  American  Institute  of 

Architects  and  of  the  Western  Association  of  Architects 
Author  of  "Elementary  Graphic  Statics  and  the  Construction  of  Trussed  Roofs" 


W.  H.  SEARLES,  C.  E. 

Author  of  "Field  Engineering"  and  "Railroad  Spiral" 

V» 

HENRY  T.  BOVEY 

Late  Rector  of  Imperial  College  of  Science  and  Technology,  London,  England 
Author  of  "Treatise  on  Hydraulics" 


WILLIAM  H.  BIRKMIRE,  C.  E. 

Author  of  "Planning  and  Construction  of  High  Office  Buildings."  "Architectural  Iron 
and  Steel,  and  Its  Application  in  the  Construction  of  Buildings."  "Compound 
Riveted  Girders,"  "Skeleton  Structures,"  etc. 


Authorities  Consulted— Continued 


IRA  O.  BAKER,  C.  E. 

Professor  of  Civil  Engineering,  University  of  Illinois 

Author  of  "A  Treatise  on  Masonry  Construction,"  "Engineers'  Surveying  Instruments, 
Their  Construction,  Adjustment,  and  Use,"  "Roads  and  Pavements" 


JOHN  CLAYTON  TRACY,  C.  E. 

Assistant    Professor    of    Structural    Engineering,     Sheffield    Scientific    School,     Yale 

University 
Author  of  "Plane  Surveying:  A  Textbook  and  Pocket  Manual" 


FREDERICK  W.  TAYLOR,  M.  E. 

Joint  Author  of  "A  Treatise  on  Concrete,  Plain  and  Reinforced" 
V» 

J.  B.  JOHNSON,  C.  E. 

Author  of  "Materials  of  Construction;"  Joint  Author  of  "Design  of  Modern  Frame 
Structures" 

V 

FRANK  E.  KIDDER,  C.  E.,  Ph.  D. 

Consulting  Architect  and  Structural  Engineer;  Fellow  of  the  American  Institute  of 
Architects 

Author  of  "Architect's  and  Builder's  Pocketbook,"  "Building  Construction  and  Super- 
intendence, Part  I,  Masons'  Work;  Part  II,  Carpenters'  Work;  Part  III,  Trussed 
Roofs  and  Roof  Trusses,"  "Strength  of  Beams,  Floors,  and  Roofs" 

^» 

WILLIAM  H.  BURR,  C.  E. 

Professor  of  Civil  Engineering,  Columbia  University;  Consulting  Engineer;  American 

Society  of  Civil  Engineers;  Institution  of  Civil  Engineers 
Author  of  "Elasticity  and  Resistance  of  the  Materials  of  Engineering;"  Joint  Author  of 

"The  Design  and  Construction  of  Metallic  Bridges,"   "Suspension  Bridges,  Arch 

Ribs,  and  Cantilevers" 


WILLIAM  M.  GILLESPIE,  LL.  D. 

Formerly  Professor  of  Civil  Engineering  in  Union  University 

Author  of  "Land  Surveying  and  Direct  Leveling,"  "Higher  Surveying" 


GEORGE  W.  TILLSON,  C.  E. 

Past  President  of  the  Brooklyn  Engineers'  Club;  American  Society  of  Civil  Engineers; 

American  Society  of  Municipal  Improvements 
Author  of  "Street  Pavements  and  Street  Paving  Material" 


CHARLES  E.  FOWLER 

Consulting  Civil  Engineer;  Member,  American  Society  of  Civil  Engineers 
Author  of  "Practical  Treatise  on  Subaqueous  Foundations" 

^« 

W.  M.  PATTON 

Late  Professor  of  Engineering  at  the  Virginia  Military  Institute 
Author  of  "A  Treatise  on  Civil  Engineering" 


Foreword 


OF  all  the  works  of  man  in  the  various  branches  of  en- 
gineering, none  are  so  wonderful,  so  majestic,  so  awe- 
inspiring  as  the  works  of  the  Civil  Engineer.  It  is  the  Civil 
Engineer  who  throws  a  great  bridge  across  the  yawning  chasm 
which  seemingly  forms  an  impassable  obstacle  to  further 
progress.  He  designs  and  builds  the  skeletons  of  steel  to  dizzy 
heights,  for  the  architect  to  cover  and  adorn.  He  burrows 
through  a  great  mountain  and  reaches  the  other  side  within  a 
fraction  of  an  inch  of  the  spot  located  by  the  original  survey. 
He  scales  mountain  peaks,  or  traverses  dry  river  beds,  survey- 
ing and  plotting  hitherto  unknown,  or  at  least  unsurveyed, 
regions.  He  builds  our  Panama  Canals,  our  Arrow  Rock  and 
Roosevelt  Dams,  our  water-works,  filtration  plants,  and  prac- 
tically all  of  our  great  public  works. 

C.  The  importance  of  all  of  these  immense  engineering 
projects  and  the  need  for  a  clear,  non-technical  presentation  of 
the  theoretical  and  practical  developments  of  the  broad  field 
of  Civil  Engineering  has  led  the  publishers  to  compile  this 
great  reference  work.  It  has  been  their  aim  to  fulfill  the  de- 
mands of  the  trained  engineer  for  authoritative  material  which 
will  solve  the  problems  in  his  own  and  allied  lines  in  Civil 
Engineering,  as  well  as  to  satisfy  the  desires  of  the  self-taught 
practical  man  who  attempts  to  keep  up  with  modern  engineer- 
ing developments. 


C.  Books  on  the  several  divisions  of  Civil  Engineering  are 
many  and  valuable,  but  their  information  is  too  voluminous  to 
be  of  the  greatest  value  for  ready  reference.  The  Cyclopedia  of 
Civil  Engineering  offers  more  condensed  and  less  technical 
treatments  of  these  same  subjects  from  which  all  unnecessary 
duplication  has  been  eliminated;  when  compiled  into  nine 
handy  volumes,  with  comprehensive  indexes  to  facilitate  the 
looking  up  of  various  topics,  they  represent  a  library  admirably 
adapted  to  the  requirements  of  either  the  technical  or  the 
practical  reader. 

C.  The  Cyclopedia  of  Civil  Engineering  has  for  years  occupied 
an  enviable  place  in  the  field  of  technical  literature  as  a 
standard  reference  work  and  the  publishers  have  spared  no 
expense  to  make  this  latest  edition  even  more  comprehensive 
and  instructive. 

C.  In  conclusion,  grateful  acknowledgment  is  due  to  the  staff 
of  authors  and  collaborators — engineers  of  wide  practical  ex- 
perience, and  teachers  of  well  recognized  ability  —  without 
whose  hearty  co-operation  this  work  would  have  been  im- 
possible. 


Table   of  Contents 


VOLUME  IV 
ESTIMATING        .        ...        .        .        By  Henry  Jackson  Burtf      Page  *11 

Estimating  Structural  Steel  for  Buildings:  Units— Degrees  of  Accuracy— Varia- 
tion from  Theoretical  Weight — Basis  of  Estimates — Estimating  Weights:  Forms. 
Listing  Material,  Standard  Material,  Computing  Weights,  Checking,  Approxi- 
mate Estimates— Estimating  Costs:  Plain  Material,  Transportation  from  Mill  to 
Shop,  Shop  Detail  Drawings,  Paint  and  Painting,  Transportation  from  Fabri- 
cating Shop  to  Building  Site,  Profit,  Summary 

STATICS     .        ....        .        .    By  Edward  R.  Maurer        Page  45 

Graphical  Representation  of  Forces — Resultant  and  Composition — Analysis  of 
Trusses— Method  of  Joints— Truss  Loads— Snow  Loads— Wind  Pressure— Apex 
Loads— Stress  Diagrams-  Method  of  Sections 

ROOF  TRUSSES        .        .        .  .       By  Frank  O.  Dufour        Page  123 

Classification  of  Trusses— Physical  Analysis  of  Trusses— Wind  Pressure  and  Snow 
Loads— Weights  of  Trusses— Roof  Coverings  (Slate,  Tin,  Corrugated  Steel,  etc.) 
— Non-Condensing  Roofing — Rafters  and  Purlins — Bracing — Spacing  and  Pitch  of 
Trusses — Steel  Truss-Bent — Suspended  Loads — Details  of  Trusses— Expansion 
Bearings — Eaves  Details— Column  and  Truss  Connections — Ventilators — Specifica- 
tions for  Structural  Work— Stress  Sheet— Methods  of  Glazing— Rivets— Design  of 
a  Riveted  Roof  Truss— Purlins,  Tension  and  Compression  Members— Lateral  Brac- 
ing—Chord Splices— Clip  Angles— Masonry  Plate— Estimate  of  Cost— Mill  Build- 
ing Construction— Runway  Girders— Crane  Reactions 

CIVIL  ENGINEERING  SPECIFICATIONS  AND  CONTRACTS     .... 

;        .       ,        .        .         By  Richard  I.  D.  Ashbridge        Page  221 

General  Instructions:  Engineering — Contract — Drawings — Specifications — Ma- 
terials Employed— Extra  Work— Dividing  Line  Between  Contracts— Verbal 
Information— Mistakes— General  Provisions:  General  Drawings— Record  Draw- 
ings—Notes upon  Drawings— Verbal  Agreements— Lines  and  Grades  by  Engi- 
neer—Measurements—Duties of  Contractors— Materials— Time— Prices— Inspec- 
tion—Builders'  Insurance— Sanitary  Regulations  —  Liability  of  Contractor- 
Damages— Alterations— Payment— Release  of  Liens— Agreement— Bond— Rail- 
road Grading:  Location  of  Work— Clearing— Excavation— Culverts— Ditches- 
Measurements  —  Foundations  —  Masonry — Cement— Concrete— Lumber — Steel — 
Wrought  Iron — Cast  Iron — Paving — Terra-Cotta  Pipe  Culverts — Cast-Iron  Pipe 
Culverts— Specifications:  Steel  Bridges— Tunnels— Pile  Trestle— Elevated  Tanks 
and  Stand  Pipes — Stone  Road — Track  Laying — Ballasting  and  Surfacing — Cross- 
Ties—Overhead  Construction  of  Electric  Railway— Pavements  and  Curbing— 
Contracts:  Parties  —  Essential  Elements  —  Corporations  —  Signatures—  Mutual 
Consent— Consideration— Guaranty— Bond— Arbitrators— Strikes,  Floods,  etc.— 
Data— Seals— Witnesses— Proposals:  Notice  to  Bidders— Instructions  to  Bidders 
—Guaranty— Advertisements— Practice  in  Specification  and  Contract  Writing 

REVIEW  QUESTIONS       .       .        .  .       .       ...       .       Page  399 

INDEX Page  407 


*  For  page  numbers,  see  foot  of  pages. 

t  For  professional  standing  of  author,  see  list  of  Authors  and  Collaborators  at 
front  of  volume. 


ESTIMATING 


ESTIMATING  STRUCTURAL  STEEL 
FOR  BUILDINGS 

The  estimating  of  structural  steel  naturally  divides  into  two 
parts,  viz,  computing  the  weights;  and  applying  the  unit  prices 
to  the  weights.  Each  of  these  parts  is  subdivided  into  a  number 
of  items  as  discussed  later. 

Units.  The  weights  of  steel  are  expressed  in  pounds  and  the 
prices  in  cents-per-pound,  or,  for  convenience,  larger  units  may  be 
used  for  the  final  results,  as  dollars-per-ton. 

The  ton  here  used  is  the  short  ton  of  2000  pounds.  As  steel 
rails  and  some  other  steel  products  are  sold  by  the  long  ton  of  2240 
pounds,  it  is  desirable  in  contracts  and  other  formal  papers  to  state 
definitely  that  the  unit  of  weight  is  the  ton  of  2000  pounds.  The 
same  ambiguity  exists  in  reference  to  the  term  hundredweight 
(cwt.),  which  may  mean  100  pounds  (7V  of  a  short  ton,  American) 
or  112  pounds  (?-$  of  a  long  ton,  British).  The  term,  one  hundred 
pounds,  is  preferred  as  being  more  definite.  There  is  not  likely  to 
be  any  confusion  as  to  the  meaning  of  these  terms  within  the  United 
States,  but  for  export  or  import  transactions  the  matter  is  important. 

The  unit  weights  of  steel  and  the  corresponding  ones  of  cast 
iron  are  shown  in  Table  I. 

Degree  of  Accuracy.  The  accuracy  of  an  estimate  varies  with 
the  data  on  which  it  is  based  and  the  purpose  for  which  it  is  used. 

The  data  may  consist  only  of  the  general  dimensions,  type  of 
construction,  and  loading  of  the  building,  yet  from  these  items  an 
estimate  can  be  made  which  will  be  correct  within  10  per  cent — 
sufficiently  accurate  for  preliminary  use.  At  the  other  extreme,  the 
data  may  consist  of  shop  detail  drawings  or  completely  detailed 
plans,  and  the  estimate  be  exact  so  far  as  computations  are  con- 
cerned; subject,  however,  to  the  allowed  variation  of  the  rolled 
section  from  its  theoretical  weight,  and  to  the  judgment  of  the 
estimator  as  to  unit  prices. 


11 


ESTIMATING 

TABLE  I 
Unit  Weights  of  Steel  and  of  Cast  Iron 


UNITS 

WEIGHTS 

Steel 

Cast  Iron 

(lb.) 

(lb.) 

Cube, 

12"X12* 

X12" 

490.0 

450.  0 

Plate, 
Bar, 

12'  X   1" 
1*X   1* 

X12* 

X12" 

40.8 
3.4 

37.5 
3.125 

Cube, 

rx  i* 

x  r 

0.283 

0.261 

The  data  usually  available  consists  of  design  drawings  which 
show  the  sections  of  all  members  but  which  are  not  complete  as  to 
connections  and  other  details.  From  such  data  the  weight  can  be 
computed  with  a  difference  of  less  than  1  per  cent  from  scale  weights 
of  the  finished  material. 

The  fabricator's  estimate  of  the  cost  of  the  finished  material 
should  be  satisfactory  to  him  if  it  is  within  2  per  cent  of  the  actual 

COSt: 

Variation  from  Theoretical  Weight.  Specifications  for  struc- 
tural steel  recognize  and  limit  the  variations  in  weight  from  the 
computed  weight  due  to  slight  inaccuracies  in  rolling  the  material. 
The  Standard  Specifications  for  Structural  Steel  for  Buildings,  of 
the  American  Society  for  Testing  Materials,  contain  the  fol- 
lowing : 

PERMISSIBLE  VARIATIONS.  The  cross  section  or  weight  of  each 
piece  of  steel  shall  not  vary  more  than  2.5  per  cent  from  that  specified;  except 
in  cases  of  sheared  plates,  which  shall  be  covered  by  the  following  permissible 
variations  to  apply  to  single  plates: 

(a)  WHEN  ORDERED  TO  WEIGHT: 

For  plates  12J  pounds  per  square  foot  or  over: 

Under  100  inches  in  width,  2.5  per  cent  above  or  below  the  specified  weight; 

100  inches  in  width  or  over,  5  per  cent  above  or  below  the  specified  weight. 
For  plates  under  12$  pounds  per  square  foot: 

Under  75  inches  in  width,  2.5  per  cent  above  or  below  the  specified  weight; 

75  to  100  inches  in  width,  5  per  cent  above  or  3  per  cent  below  the  specified  weight; 

100  inches  in  width  or  over,  100  per  cent  above  or  3  per  cent  below  the  specified  weight. 

(b)  WHEN  ORDERED  TO  GAGE: 

The  thickness  of  each  plate  shall  not  vary  more  than  0.01  inch  under  that  ordered. 

An  excess  over  the  nominal  weight  corresponding  to  the  dimensions  on  the  order  shall  be 
allowed  for  each  plate,  if  not  more  than  that  shown  in  Table  II;  1  cubic  inch  of  rolled  steel  being 
assumed  to  weigh  0.283  pound. 


ESTIMATING 


TABLE  II 
Plate  Variations 


ALLOWABLE  EXCESS 

(Expressed  as  Percentage  of  Nominal  Weight,  for 
Plate  Widths  Indicated) 

THICKNESS 
ORDERED 

NOMINAL 
WEIGHT 

50 

70 

75 

100 

115 

(in.) 

(Ib.  per  sq.  ft.) 

Under 

Inches 

Inches 

Under 

Inches 

Inches 

Inches 

50 

to  70 

or 

75 

to  100 

to  115 

or 

Inches 

Inches 

Over 

Inches 

Inches 

Inches 

Over 

cS 

(per 
cent) 

(per 
cent) 

(per 
cent) 

(per 
cent) 

(per 
cent) 

(per 
cent) 

|to* 

5.10to    6.37 

10 

15 

20 

A  to  A 

6.  37  to    7.65 

8.5 

12.5 

17 

A  to    i 

7.65  to  10.20 

7 

10 

15 

i 

10.20 

10 

14 

18 

"iS 

12.75 

8 

12 

16 

1 

15.30 

7 

10 

13 

17 

TS 

17.85 

6 

8 

10 

13 

A 

20.40 
22.95 

5 
4.5 

7 
6.5 

9 
8.5 

12 
11 

1 

25.50 

4 

6 

8 

10 

Over  f 

3.5 

5 

6.5 

9    ! 

The  variations  stipulated  apply  to  the  individual  prices  of 
steel.  Some  will  overrun,  others  underrun;  very  few  pieces  will  have 
the  maximum  variations.  Hence  it  may  be  expected  that  the 
actual  total  weight  of  a  large  number  of  pieces  will  not  vary  much 
from  the  computed  weight.  This  is  confirmed  by  experience  so  that 
no  allowance  for  the  variation  is  made.  However,  the  foregoing 
may  not  be  true  if  there  is  a  large  percentage  of  plates,  for  plates 
are  more  likely  to  overrun  than  to  underrun,  particularly  if 
ordered  to  gage  or  thickness.  In  such  case  an  allowance  for 
overrun  may  be  proper.  Its  amount  must  be  determined  from 
the  conditions. 

Cast  iron  varies  from  the  computed  weight  even  more  than  steel, 
due  to  inaccuracy  of  patterns,  shrinkage  in  cooling,  and  other  causes. 
It  is  more  likely  to  overrun  than  underrun  and  it  is  proper  to  add 
a  percentage.  Three  per  cent  is  a  reasonable  average  allowance, 
although  individual  items  may  vary  much  more  than  this. 

Basis  of  Estimates.  Estimates  are  commonly  based  on  the 
net  weight  of  the  finished  structural  steel,  but  in  special  cases  it 
may  be  necessary  to  compute  the  gross  weight  of  the  material  used 
in  producing  the  fabricated  steel.  The  difference  in  weight  is 
represented  by  the  punchings,  cut  corners,  and  other  waste.  The 


ESTIMATING 


Kfij 

x's-i 

S  33 
1* 


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ZZ   .. 

**!£ 


§c-?io 
C^HC 


o  o  •*  •*  oo  co  <r>  TJI  o 

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i  i 

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g  £  g^^oc^t^oTiiiooo^s         ooco^;00^030005^^* 

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^odddddd      fei       _  JJIIIJ|gI 

t       _i  __._._,_..     

X, 


ESTIMATING  5 

net  weight  is  the  amount  delivered  by  the  fabricator  to  the  pur- 
chaser; the  gross  weight  is  the  amount  purchased  by  the  fabricator 
from  the  rolling  mill. 

The  price  which  is  paid  by  the  purchaser  to  the  fabricator  is 
based  on  the  material  to  be  furnished  and  its  place  of  delivery, 
and  may  include  painting  and  erection.  The  basis  must  be  stated 
definitely  in  all  transactions.  The  price  may  be  a  lump  sum  or 
a  price  per  ton. 

ESTIMATING  WEIGHTS 

The  operations  involved  in  estimating  weights  consist  of  listing 
the  items  and  of  computing  the  weights  therefrom. 

The  listing  is  usually  done  on  forms  printed  for  that  purpose. 
In  preparing  such  forms  and  in  using  them,  due  attention  is  given 
to  the  orderly  arrangement  of  items  and  to  the  classification  required 
for  computing  costs. 

Forms.  Fig.  1  is  a  form  for  listing  and  computing  the  detailed 
weights  and  Fig.  11  is  a  form  used  as  a  summary.  On  the  latter 
are  spaces  for  the  general  data  relating  to  the  job.  These  need  not 
be  repeated  on  the  detail  sheets,  but  each  detail  sheet  must  contain 
enough  data  in  the  headings  to  identify  it  and  facilitate  checking. 
Usually  the  name  of  the  structure,  the  portion  on  the  sheet,  and 
the  drawing  number  from  which  it  is  taken  are  sufficient.  The 
initials  of  the  estimator,  the  computer,  and  the  checker  are  desirable, 
also  the  date  when  take-off  was  made.  Page  numbers  are  essential. 
In  recording  the  drawing  number  note  also  the  date  of  the  drawing 
and  the  date  of  latest  revision. 

Classification.  As  the  classification  varies  with  different  jobs 
it  is  not  practicable  to  have  the  headings  printed  on  the  forms. 
They  must  be  filled  in  as  the  estimate  develops.  As  each  item  is 
listed  its  classification  is  noted  in  the  column  provided  for  that 
purpose. 

Generally,  the  material  is  divided  into  beam  work  and  riveted 
work.  These  may  be  divided  into  a  number  of  classes  as  fol- 
lows: 

Beam  Work,  (a)  Punching  one  size  of  hole  in  web  only,  or 
one  size  of  hole  in  one  or  both  flanges;  (b)  punching  one  size  of  hole 
in  web  and  in  one  or  both  flanges;  (c)  punching  two  sizes  of  holes 


15 


6  ESTIMATING 

in  web  only  or  two  sizes  of  holes  in  one  or  both  flanges;  (d)  coping, 
ordinary  beveling,  riveting,  or  bolting  connection  angles,  and  assem- 
bling into  girders  with  separators,  including  any  additional  punching; 
(r)  riveting  on  cover  plates  and  shelf  angles;  and  (f)  fittings,  includ- 
ing all  rivets,  bolts,  separators,  bearing  plates,  anchors,  and  con- 
nection angles,  except  such  as  are  attached  to  beams  (r) .  Connection 
material  which  will  be  attached  to  columns  or  girders  is  classified 
as  column  material  or  girder  material,  respectively,  although  as 
a  matter  of  convenience  it  is  listed  at  the  time  the  beams  are 
taken  off. 

Riveted  Work.  Columns;  plate  girders  without  cover  plates; 
plate  girders  with  cover  plates;  lattice  girders;  and  trusses. 

The  classes  may  be  still  further  subdivided  if  required,  and  in 
addition  there  may  be  items  such  as  cast-iron  base  plates,  cast-iron 
columns,  tie-rods,  curved  beams,  etc. 

In  addition  to  the  classification  as  to  work  there  may  be  a 
classification  as  to  cost  of  the  plain  material.  This  is  discussed 
under  Estimating  Costs. 

Listing  Material.  Listing  material,  or  "take-off",  consists  of 
making  a  list  on  the  estimate  sheets  of  all  the  items  of  steel  called 
for  on  the  plans.  They  may  be  written  in  the  form  given  in 
Fig.  1.  The  first  column  contains  the  number  of  pieces,  the  second 
the  section,  the  third  the  weight  per  lineal  foot,  the  fourth  the 
length,  and  the  fifth  the  classification.  If  the  weight  per  lineal 
foot  is  not  given  on  the  drawings,  it  can  be  taken  from  the 
hand  books.  This  will  be  required  for  most  sections  other  than 
beams  and  channels.  The  arrangement  of  items  given  above  is 
arbitrary  and  may  be  varied  by  different  estimators  or  for  differ- 
ent parts  of  the  work.  The  material  listed  in  Fig.  1  is  taken 
from  Fig.  2. 

Usually  the  framing  plans  of  a  building  show  only  the  material 
for  the  main  numbers.  The  connections  are  left  to  the  detailer 
to  develop  with  more  or  less  control  by  provisions  in  the  speci- 
fications. For  the  connections  of  beams  to  beams,  standard  con- 
nections are  commonly  used;  for  connections  of  beams  to  columns 
and  in  general  all  other  connections  it  is  required  that  the  full 
strength  of  the  member  shall  be  developed.  The  estimator  must 
supply  all  such  details,  including  rivets,  bolts,  fillers,  etc.  In  some 


ESTIMATING 


cases  it  may  be  necessary  for  him  to  sketch  out  the  details  in  order 
to  determine  the  material  required  for  them. 

The  lengths  may  be  recorded  in  feet  and  inches,  or  in  feet 
using  decimals.  The  lat- 
ter is  more  convenient  if 
the  computations  are  made 
by  machine.  The  nearest 
inch  or  the  nearest  tenth 
of  a  foot  is  sufficiently 
accurate  for  most  pur- 
poses. A  large  number  of 
small  pieces  of  one  length 
may  make  it  desirable  to 
record  the  lengths  more 
accurately. 

The  lengths  of  indi- 
vidual pieces  are  not  given 
on  the  drawings  but  must 
be  computed  as  nearly  as 
practicable  from  the  dimen- 
sions given.  The  dimen- 
sions usually  given  are  the 
distances  from  center  to 
center  of  columns,  the  dis- 
tances from  column  cen- 
ters to  beams  and  the 
story  heights.  In  listing 
lengths  the  estimator  must 
allow  for  widths  of  col- 
umns, thickness  of  girder 
webs,  clearance  at  ends  of 
beams,  position  of  column 
splices,  and  any  other  ele- 
ments affecting  the  actual 
length  of  material  required. 

Beams  require  about  j-inch  clearance  at  each  end.  Tie-rods 
are  about  4  inches  longer  than  the  distance  from  center  to  center 
of  beams. 


8 


ESTIMATING 


The  estimator  should  establish  and  adhere  to  a  definite  order 
of  procedure  in  taking  off  the  quantities.  A  preliminary  review 
of  all  the  drawings  will  indicate  the  following:  order  in  which  they 


"State-and-Adams"  Building 


Columns  1,  2,  3.  4  (SB.— 4th). 
Drawing  S9.  dated  11-28-14. 


Estimate     made  by  N.O.H.;  checked  by  H.X.K. 
Extensions  made  by  N.O.H.;  checked  by  H.N.R. 
Estimate  No.  C1080. 
Date  1-22-15.     Page  25,  of  48. 


No. 

SECTION 

WEIGHT 
(Ib.  per 
lin.  ft.) 

LENGTH 

(ft.) 

WEIGHT        TOTALS 

LARGE 
ANGLES 

SB.  to  1st 

2 

PI.   14x  £ 

23.8 

29.3 

} 

(Col.  1)     1 

4 

Ls     8x6  xf 

28.5 

29.3 

12,805 

3,340 

2 

PL   18x2J 

137.7 

29.3 

4 

PL   14x  £ 

23.8 

32.2 

(Cols.  2,  3)^ 

8 
2 

Ls     8x6  xS- 

Pl.   16x2  \ 

28.5 
136.0 

32.2 
32.2 

•  29,508 

7,342 

2 

PL   18x2f 

160.6 

32.2 

2 

PL   14x  } 

23.8 

34.3 

(Col.  4)     « 

4 
2 

Ls     8x6  xf 
PL   18x2| 

28.5 
145.4 

34.3 
34.3 

15,517 

3,910 

(Bottom) 

8 

Ls     8x3gxf 

27.5 

1.0 

220 

220 

(Splice) 

8 

PL   16x  | 

40.8 

2.5 

816 

(Splice) 

8 

12x  i 

20.4 

1.5 

245 

Rivets  3^% 

2,069 

61,180 

H 

6 
1 
12 

Is*  to  2nd 
PL   14x  } 
14x  f 
Ls      6x6  x| 

23.8 
29.8 
24.2 

19.6 
19.6 
19.6 

32,634 

2,234 

4 

8x6  x| 

28  5 

19  6 

8 

PL   16x2  \ 

136.0 

19.6 

17,046 

8 

16x  f 

40.8 

2.5 

816 

8 

12x  \ 

20.4 

1.5 

245 

Rivets  3|70 

1,179 

34,874 

2nd  to  4th 

4 

PL   14x  f 

29.8 

28.2 

16 

Ls     6x6  xf 

24.2 

28.2 

4 

PL    16x2 

108.8 

28.2 

40,360 

2 

16x2| 

115.6 

28.2 

2 

16x2| 

129.2 

28.  2 

8 

16x  f 

40.8 

2.5 

816 

8 

12x  | 

20.4 

1.5 

245 

Rivets  3i% 

1,450 

42,871 

Page  Total 

138,92.5  Ib. 

"JOTS. — Connections  for  floor  framing  are  listed  with  beams. 
Fig.  3.     List  of  Material  for  Colut 


should  be  taken  off,  usually  beginning  with  No.  1  and  continuing 
in  sequence;  what  drawings  must  be  used  together,  as  when  the 
spandrel  sections  are  shown  on  a  certain  drawing  and  their  con- 


ESTIMATING 


9 


Col.  No. 
9* 


5th 


V* 


nections  on  another;  and  what  drawing  to  use  when  the  same  items 
are  shown  in  two  places,  as  when  the  make-up  of  a  plate  girder 
is  given  on  the  floor  plan  and  a  complete  detail  of  it  on  another 
drawing. 

In  taking  off  a  floor  framing  plan,  begin  at  a  certain  point 
and  proceed  in  an  orderly  way.  It  is  sometimes  convenient  to 
take  off  all  the  beams  in  an 
east  and  west  direction  and 
then  those  in  a  north  and 
south  direction,  as  shown  in 
Fig.  1.  As  each  item  is  listed 
it  is  checked  on  the  drawing. 
After  all  the  beams  in  a  floor 
or  any  convenient  group  have 
been  listed,  check  the  number 
by  counting  from  the  plan  and 
comparing  with  the  number 
listed.  After  the  beams  are 
listed,  the  details  for  a  com- 
plete floor  or  other  subdivision 
are  taken  off.  These  are  beam 
connections,  column  connec- 
tions, separators,  diaphragms, 
tie-rods,  etc.  Ordinarily,  con- 
nections are  not  delineated  on 
the  drawings  but  must  be  sup- 
plied by  the  estimator.  Stand- 
ard beam  connections  are  used 
wherever  they  will  suit.  As 
there  are  no  well-established 
standard  column  connections  they  must  be  sketched  out  unless  the 
estimator  knows  from  experience  the  material  required  for  them. 

Fig.  3  gives  the  list  of  column  material  taken  from  Fig.  4. 
In  taking  off  the  material  from  a  column  schedule,  it  usually  is 
easier  to  group  the  items  in  tiers,  rather  than  in  stacks.  Thus  in 
Fig.  3,  the  first  group  is  from  sub-basement  (SB.)  to  first  floor,  the 
second  group  from  first  floor  to  second  floor,  etc.  The  lengths  in 
the  first  group  will  vary  as  indicated;  also  they  are  greater  than  the 


flt 


*1S 
§^ 


. 

Y  OJ 


4 


sis 


I 


Fig.  4.     Part  of  Column  Schedule 


19 


10 


ESTIMATING 


distance  from  floor  to  floor,  including  the  part  extending  below 
the  sub-basement  floor  and  that  from  the  first  floor  to  the  splice. 
If  there  is  nothing  on  the  plans  to  indicate  the  exact  position  of 
the  splice,  it  can  be  assumed  to  be  2  feet  above  the  floor  level. 

In  the  example  given  in  Fig.  3  the  web  plates  are  listed,  then 

the  angles,  and  then  the  flange  plates.     The  number  of  pieces  can 

be  checked  easily  by  counting,  and  in  case  of  a  discrepancy  the  error 

can  be  located  without  difficulty.     After  the  members  of  the  column 

"State-and=Adams"  Building 

Cast-Iron  Base  Plates  for  Columns. 
Drawing  S9,  dated  11-28-14. 


Estimate     made  by  J.J.I,.;  checked  by  H.N.R. 
Extensions  made  by  J.J.L.;  checked  by  H.X.R 
Estimate  No.  C10SO. 
Date  1-22-15.     Page  34,  of  48. 


Xo. 

SECTIOX 

WEIGHT 
(Ib.  per 
lin.  ft.) 

LENGTH 
(ft.) 

WEIGHT 
(Ib.)     - 

TOTALS 

(Bottom 
(Hub) 
(Flange) 

(Ribs) 
(Rim) 

8 
1 

5  Bases,  for  Cols. 
1,  2,  7,  17,  18  (Each) 
PI.     52'  diam.x3*  metal 
Cyl.  19'  diam.x.3'  metal 
PL    27'  diam.,  less  13' 
diam.x2'  metal 
PL     l(H'x2' 
PL      7'x2' 
Fillets  and  overrun 

2.1 

2.1 
10.2 

7% 

1,662 

986 

230 
1,070 
446 
307 

Total  for  1  base 

4,701 

(Deduct) 

5 
5 

Total  for  5  bases 

Steel  Bearing  Plate* 
PL  27'x2' 
Comers,  7£'x2' 

183.6 
51.0 

2.2 

1.2 

2,020 
306 

23,505 

1,714 

Page  Total 

25,219  Ib. 

Fig.  5.     List  of  Material  for  Cast-iron  Base  Plates 

sections,  the  details  for  that  tier  follow.  The  details  consist  of  rivet 
heads,  splice  plates,  fillers,  and  connections  for  joists  and  girders. 
The  rivets  may  be  taken  by  an  approximate  count,  or  a  percentage 
may  be  applied  to  cover  them.  Care  must  be  taken  to  avoid  dupli- 
cating joist  and  girder  connections  to  columns.  These  items  may 
be  taken  off  with  the  floor  framing,  but  if  so,  are  classed  as  column 
material.  Strict  attention  to  the  established  order  of  procedure 
will  prevent  such  duplication.  In  this  example  the  beam  connec- 
tions have  been  taken  with  the  floor  framing,  and  the  girder  con- 
nections with  the  girders. 


20 


ESTIMATING 


11 


Fig.  5  gives  the  list  of  material  for  the  cast-iron  base  shown 
in  Fig.  6.  The  ribs  are  listed  as  equivalent  rectangular  plates, 
the  length  being  the  distance  between  the  top  and  bottom  plates; 
the  rim  as  a  rectangular  plate  or  bar,  whose  length  is  the  circum- 
ference of  its  median  line,  less  the  thickness  of  ribs  which  intersect 
it;  the  base  as  a  circular  plate;  the  top  as  a  circular  plate  from 
which  the  central  part  is  deducted;  the  hub  as  a  cylinder  described 
by  its  wall  thickness  and  depth,  the  latter  being  the  distance  between 
the  top  and  bottom  plates.  An 
arbitrary  percentage  is  added  to 
cover  the  fillets  and  the  proba- 
ble overrun  in  weight,  7  per  cent 
being  used  in  this  case. 

Fig.  7  is  an  estimate  of  the 
plate  girder  shown  in  Fig.  8.  The 
beveled  gusset  plates  are  listed  as 
the  equivalent  rectangular  plates 
(or  the  extreme  dimensions  may 
be  used  and  the  beveled  corners 
deducted) .  The  rivet  heads  may 
be  counted  or  a  percentage  used 
to  cover  them.  For  girders  with- 
out cover  plates  use  3  per  cent 
and  with  cover  plates  5  per 
cent. 

Standard  Material.  Items 
which  have  been  standardized 
need  not  be  listed  in  detail. 
Table  III  gives  the  standard 
weights  used  by  the  American 

Bridge  Company  for  the  connections  of  beams  to  beams,  connections 
of  beams  to  columns,  bearing  plates,  and  anchors.  These  standards 
are  not  used  in  all  cases,  and  may  be  changed  from  time  to  time, 
so  the  estimator  must  determine  whether  they  apply  to  the  case 
in  hand  before  using  them. 

The  weights  of  beam  connections,  bearing  plates,  beam  anchors, 
cast-iron  separators,  rivet  heads,  bolts,  nuts,  etc.,  are  given  in 
most  of  the  handbooks,  to  which  reference  should  be  made.  The 


Fig.  6.  Cast-iron  Base  Plate 


21 


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ESTIMATING 


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ESTIMATING 


13 


weights  of  connections  there  given  should  be  checked  to  determine 
whether  rivet  heads  are  included. 

In  the/ estimate,  Fig.   1,  the  weights  of  column  connections 
used  are  those  given  in  Table  III.     They  are  for  shelf  or  bracket 

"State=and=Adams"  Building 


Spandrel  Girders,  4th,  5th,  and  6th  floors 

(between  col.  13-14,  and  col.  17-18). 
Drawing  S8,  dated  11-28-14. 


Estir 

Exte 

Estimate  No.  C1080. 

Date  1-22-15.     Page  20,  of  48. 


te     made  by  J.J.L.;  checked  by  H.N.R. 
>ns  made  by  J.J.L.;  checked  by  H.N.R. 


Xo.                       SECTION 

WEIGHT 
(Ib.  per 
lin.  ft.) 

LFN-GTH 
(ft.) 

WEIGHT 

TOTALS 

LARGE 
ANGLES 

3  Girders,  betw.  Col. 

13  and  14  (Each) 

1 

PI.  20"xA" 

21.2 

15.2 

322 

3 

Ls  3£x3|x 

8.5 

17.2 

439 

1 

6  x3Jx 

11.7 

17.2 

201 

8 

3  x3  x 

7.2 

1.0 

58 

1 

6  x6  x 

28.7 

3.3 

95 

1 

8  x6  xl 

44.2 

3.3 

146 

146 

1 

6  x3|x| 

18.9 

3.3 

62 

4 

PI.  12xA 

12.8 

1.1 

56 

2 

6xj 

5.1 

1.1 

11 

2 

(Deduct)  12ffx^" 

36.3 
22.9 

3.3 
1.0 

}     217 

134 

Rivets  |ff 

.33 

44 

150 

Rivets  i" 

.50 

75 

12 

Ring  fillers 

.50 

6 

Total  for  1  girder 

1,732 

Total  for  3  girders 

5,196 

432 

3  Girders,  betw.  Col. 

17  and  18  (Each) 

(Same  as  13-14,  and 

add) 

1,732 

146 

1 

PL  20"x^" 

21.2 

1.2 

25 

3 

Ls  3ix3sx 

8.5     !       1.2 

31 

1 

6  x3ix 

11.7            1.2 

14 

10 

Rivets,  f  ' 

3 

Total  for  1  girder 

1,802 

Total  for  3  girders 

5,406 

432 

864 

Page  Total 

10,602  Ib. 

Fig.  7.     List  of  Material  for  Spandrel  Girders 


connections  with  angle  on  top.  These  may  not  apply  to  other  cases. 
The  connections  will  vary  with  the  conditions  imposed,  so  the 
estimator  should  determine  the  requirements  for  the  case  in  hand. 
It  is  desirable  to  estimate  column  connections  from  shop  details 


1  ! 


ESTIMATING 


whenever  opportunity  offers.     In  this  way  reliable  weights  can  be 
colleeted  eovering  all  ordinary  connections. 

The  rivet  heads  only  are  estimated.  The  shank  offsets  the 
material  punched  from  the  hole  which  it  fills.  In  beam  framing, 
rivet  heads  are  included  in  the  connections,  but  rivets  in  cover  plates, 
shelf  angles,  and  other  fittings  must  be  counted.  For  columns, 
plate  girders,  and  trusses  the  rivets  should  be  counted  if  the  plans 
are  in  sufficient  detail  to  permit  an  approximate  count.  Other- 
wise, a  percentage  is  applied.  The  estimator  can  accumulate 
data  as  to  the  percentage  to  use  by  counting  the  number  used  in 


Li 

Fig.  8.     Spandrel  Girder  13-14,  17-18,  at  Fourth,  Fifth,  and  Sixth  Floors 

typical  members  from  shop  detail  drawings.  In  the  absence  of 
more  accurate  data,  3  per  cent  may  be  used  for  columns,  trusses, 
and  plate  girders  without  cover  plates;  and  5  per  cent  for  plate 
girders  with  cover  plates. 

The  detail  parts  of  riveted  trusses  are  sometimes  estimated 
by  percentage.  This  is  permissible  if  the  estimator  has  data  appli- 
cable to  the  particular  truss  under  consideration.  It  is  much  better 
and  more  accurate  to  sketch  the  gusset  plates  and  other  details 
and  list  the  material  required. 

Computing  Weights.  Having  listed  the  material  the  computa- 
tion of  weights  is  simple  arithmetic.  It  must  be  done  with  con- 
sistent accuracy.  The  length  being  given  to  the  nearest  inch  may 
be  inaccurate  by  \  inch.  The  resulting  discrepancy  for  a  beam 
weighing  25  pounds  per  foot  would  be  about  1  pound.  It  is  the 


ESTIMATING  15 

usual  practice  to  record  whole  pounds  disregarding  decimals.  On 
this  basis  the  degree  of  accuracy  of  the  computations  will  be  greater 
than  that  of  the  take-off  or  that  of  the  rolled  section. 

Computing  machines  are  useful  for  extending  the  weights 
and  adding  them.  The  value  of  machine  work  as  compared  with 
mental  and  manual  calculating  depends  largely  on  the  ability  and 
skill  of  the  computer.  Neither  method  is  proof  against  error. 

In  addition  to  short  methods  of  multiplication  which  are  given 
in  textbooks  on  arithmetic  several  short  cuts  are  applicable  to  this 
work.  For  instance,  the  weight  of  an  item  involves  three  factors  — 
number  of  pieces,  length  over  all,  and  weight  per  lineal  foot  —  and  it 
involves  two  multiplications.  The  order  in  which  the  factors  are 
combined  may  affect  the  amount  of  work  in  computing.  Frequently 
one  or  perhaps  both  of  the  operations  may  be  done  mentally. 

Examples.  1.  In  the  case  of  two  18-inch  I-beams  21.4  feet  long  and 
55  pounds  per  lineal  foot  (2  Is  18"X55  lb.X21.4'),  the  factors  are  (a)  2,  (b)  55, 
(c)  21.4.  (a)  and  (b)  produce  110,  and  this  partial  product  with  (c)  gives  2354 
pounds,  all  being  done  mentally. 

2.  (a)   12  Ls  (3"X3*Xi*)X  (b)  4.9  lb.X(c)  8'-4";    (a)  and  (c)  produce 
100,  and  this  with  (b)  gives  490  pounds. 

3.  (a)  7  Cs  8"X(b)  Hi  lb.X(c)  16'-0";  (b)  and  (c)  produce  180,  and  this 
with   (a)   gives  1260  pounds. 

In  these  examples  the  proper  order  of  the  operations  is  evident 
at  a  glance. 

Several  items  in  sequence  may  have  a  common  factor,  as  a 
number  of  pieces  of  different  lengths  of  a  certain  size  of  beam  or 
angle,  or  a  list  of  column  material  all  of  one  length.  The  partial 
products  not  containing  the  common  factor  may  be  added  and  the 
common  factor  applied  to  this  sum,  as  follows: 

Example.  (a)  (b)         (c) 

2  Ls  (2rX2|"xA")X5  lb.X21'-0* 

3  Ls  (2^"X2^xA'')X51b.Xl4'-4' 
12  Ls  (2rx2rX^")X5lb.X  6'-6" 

1  Ls  (2i"X2i"XA")X51b.Xl7'-0' 

8  Ls  (2£"X2f*XA"')X5lb.Xll/-3' 
Combining  (a)  and  (c)  gives 


3Xl4'-4*  =  43' 

12  X   6'-6"  =  78' 

1X17'-0"  =  17' 

8X11-3"  =  90' 


270'-0" 


25 


16  ESTIMATING 

Then  multiplying  by  (b)  5,  gives  1350  pounds. 

(a)  (b)  (c) 

2  PL  (14' X      f')X 29.75  lb.X22'-0' 
4Ls  (  8"X6'xr)X39.1    lb.X22' 
4  PI.  (18'X      DX45.9    lb.X22' 

Combining  (a)  and  (b)  gives 

2X29.75=  59.5 
4X39.1  =156.4 
4X45.9  =183.6 

399. 5  Ib. 
Then  multiplying  by  (c)  22,  gives  8789  pounds. 

In  computing  cast-iron  members  such  as  listed  in  Fig.  4,  the 
weight  may  be  computed  from  the  weight  per  lineal  foot  of  the 
section;  or  from  the  weight  of  a  board  foot  (12" X 12" XI"),  37.5 
pounds;  or  from  the  weight  of  a  cubic  inch,  0.26  pound. 

Checking.  The  most  thorough  check  of  an  estimate  is  an 
independent  duplication  of  the  work,  including  the  take-off.  Less 
reliable,  but  more  commonly  used  is  a  complete  review  of  the  original 
estimate.  One  large  manufacturer  follows  an  intermediate  course. 
His  estimators  make  a  carbon  copy  of  the  lists  of  material,  then 
the  computations  are  made  independently  on  the  original  and 
on  the  carbon  copy. 

The  estimator  can  apply  a  number  of  checks  as  his  work  pro- 
gresses. As  each  item  is  listed  a  check  mark  is  placed  on  the  draw- 
ing. When  all  the  material  on  a  drawing  has  been  listed  the  drawing 
should  be  examined  carefully  and  systematically  to  see  that  every 
piece  of  material  is  checked.  A  further  check  on  the  take-off  is 
obtained  by  counting  the  items  as  has  been  suggested.  The  checker 
reviews  the  listing  in  the  same  manner,  placing  his  own  check  mark 
on  the  drawings  (using  a  pencil  of  a  different  color).  This  pro- 
cedure should  prevent  with  reasonable  certainty  any  omission  or 
duplication  of  items.  Correctness  of  sections  and  lengths  can  be 
assured  only  by  a  careful  review  of  these  elements. 

The  larger  features  of  the  estimate  need  to  be  examined  with 
care.  A  complete  floor,  or  a  tier  of  columns,  or  girders  shown  on 
a  special  drawing  may  be  omitted.  A  general  survey  of  the  estimate 
and  drawings  will  reveal  such  a  mistake.  On  the  other  hand,  there 
may  be  a  duplication  due  to  certain  items  being  shown  in  two  places 
on  the  drawings,  as,  plate  girders  which  may  be  specified  on  a  floor 


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ESTIMATING  17 

plan  and  detailed  on  another  drawing.  In  the  final  review  of  the 
take-off  the  large  items  should  be  counted  to  insure  that  the  correct 
number  of  floors  and  tiers  of  columns  have  been  listed;  that  beam 
and  column  details  have  been  taken  for  all  floors;  that  special  items, 
such  as  foundation  girders,  sidewalk  framing,  and  penthouses  have 
been  estimated;  and  that  all  the  drawings  of  the  set  have  been  used. 

The  common  sources  of  error  in  the  computations  are  misplaced 
decimal  points,  wrong  multiplications  and  additions,  and  omitting 
one  of  the  factors.  To  check  the  decimal  point  the  computer 
should  make  an  approximate  mental  calculation  by  which  he  can 
locate  the  decimal  point  properly  and  also  discover  any  gross  error 
in  multiplication.  The  addition  can  be  checked  by  cross  addition; 
thus,  in  Fig.  1,  the  weight  of  each  item  is  entered  in  the  last  (total) 
column  and  in  one  of  the  classified  columns;  then  at  the  bottom 
of  the  sheet  are  the  totals  for  the  classified  columns,  which,  added 
together,  must  agree  with  the  total  of  the  last  column. 

The  omission  of  one  of  the  factors  is  most  likely  to  occur  when 
a  group  of  items  is  duplicated;  thus  for  a  set  of  girders  the  material 
may  be  listed  for  one  girder  and  this  weight  multiplied  by  the  number 
of  girders.  The  last  factor  may  be  overlooked  either  in  the  take-off 
or  the  computations. 

A  careful  and  complete  review  of  the  computations,  or  better 
still,  independent  computation,  is  essential  to  insure  correctness 
in  the  detail  figures.  But  even  this  must  not  be  relied  upon  as  a 
guard  against  misplaced  decimal  points  or  omitted  factors.  Two 
estimators  may  make  the  same  error,  especially  if  one  is  reviewing 
the  work  of  the  other. 

The  sections  of  members  listed  can  be  roughly  checked  by 
reading  through  the  list  while  the  items  are  fresh  in  mind.  An 
omission,  duplication,  WTong  weight  of  beam,  wrong  dimension 
of  section,  or  WTong  length  will  most  likely  attract  attention.  Errors 
in  weights  per  lineal  foot  may  occur  by  using  the  area  instead  of 
the  weight.  A  close  scrutiny  will  disclose  this  without  comparing 
with  the  tables. 

In  many  cases  approximate  checks  may  be  secured  by  com- 
parison of  similar  items  or  groups  of  items.  The  tiers  of  columns 
in  a  high  building  should  vary  in  weight  through  the  typical  stories 
by  a  regular  difference.  Floors  which  have  nearly  the  same  framing 


27 


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ESTIMATING 


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20  ESTIMATING 

should  have  approximately  the  same  weight.  Likewise  similar 
girders  can  be  compared  by  making  allowance  for  items  which  occur 
in  one  and  not  in  the  other. 

Approximate  Estimates.  It  is  sometimes  necessary  to  have 
an  approximate  estimate  of  the  tonnage  of  steel  required  for  a  given 
structure  before  the  framework  is  designed.  Such  estimates  can 
be  made  by  comparing  with  the  known  quantities  of  steel  used  in 
structures  that  have  been  built.  The  basis  of  comparison  is  the 
cubic  foot  of  building  volume,  or  the  square  foot  of  floor  area.  The 
one  can  easily  be  converted  to  the  other  if  the  average  story  height 
is  known.  The  data  and  discussion  here  given  are  on  the  cubic- 
foot  basis. 

The  degree  of  accuracy  of  an  estimate  based  on  the  cubic 
content  of  the  building  depends  on  the  definiteness  of  the  data 
and  to  some  extent  on  the  skill  and  experience  of  the  estimator. 
The  cubic  content  must  be  computed  on  the  same  basis  in  the  example 
as  in  the  data  with  which  it  is  compared.  The  data  given  herein 
is  based  on  the  actual  cubic  content  of  the  building,  including 
penthouses,  foundations,  etc.,  and  excluding  all  open  courts. 

Table  IV  gives  the  weight  of  steel  per  cubic  foot  of  building 
volume  for  a  number  of  buildings.  The  items  are  arranged  in  order 
of  the  increase  of  the  weight  of  steel  per  cubic  foot.  Note  that 
long-span  concrete  or  tile-and-concrete  floor  construction  requires 
no  joists,  the  concrete  spanning  from  girder  to  girder.  The  flat- 
tile  arch  requires  joists  spaced  5  to  6  feet  apart.  The  weights 
given  include  cast-iron  bases,  and  steel  chimneys,  as  well  as  the 
structural  frame  of  the  building,  all  of  which  is  the  material  usually 
included  in  a  structural  steel  contract. 

In  Table  IV  all  the  pertinent  data  available  is  given,  including 
special  features  of  certain  buildings.  A  comparison  of  the  data 
discloses  some  of  the  elements  which  contribute  to  a  weight  greater 
than  the  minimum.  Other  elements,  not  shown  in  the  table,  which 
cause  high  weights  per  cubic  foot  are:  wide  column  spacing;  shal- 
low girders  (for  flat  ceilings);  heavy  live  loads;  heavy  dead  loads 
(as  partitions  in  hotels) ;  small  area,  making  a  large  percentage  of 
wall  load;  interior  walls,  or  provision  for  them;  high  buildings; 
provision  for  future  stories;  foundation  girders;  steel  in  retaining 
walls;  girders  supporting  columns;  and  low  story  heights. 


30 


ESTIMATING 


21 


To  use  this  method  of  estimating,  select  from  the  table  the 
item  which  corresponds  most  closely  with  the  case  in  hand.  If 
there  are  some  elements  not  covered  by  the  item  selected,  allow- 
ance can  be  madg  for  them;  thus  if  some  special  feature  is  required, 
it  can  be  designed  approximately  and  its  weight  added  to  that 
computed  from  the  unit  weight  selected  from  the  table. 

-  Estimators  and  designers  should  make  it  a  practice  to  develop 
data  from  their  estimates  of  all  classes  of  work  for  use  in  making 
approximate  estimates  of  future  similar  work. 


M- 


Kg, 


Panel  of  Floor  Framing 


A  comparison  of  the 
weight  of  steel  for  a 
structure  as  computed 
from  the  plans,  with  the 
approximate  weight  de- 
termined from  Table  IV 
will  serve  as  a  rough 
check  of  the  estimate ;  or, 
assuming  that  the  esti- 
mate from  the  plans  is 
correct,  the  comparison 
will  indicate  in  a  general 
way,  whether  the  design 
is  too  heavy  or  too  light. 

Another   approxi- 
mate method  of  estimating  the  weight  is  to  compute  it  from  tenta- 
tive designs  of  typical  parts. 

Illustrative  Example.  To  illustrate  this  method,  assume  the 
following  data  for  a  building:  length  lOO'-O";  width  lOO'-O"; 
height — 12  stories  above  grade  and  1  basement — equals  160  feet 
from  basement  floor  to  roof;  column  spacing,  approximately,  20' — 0" 
X20'-0";  dead  load  on  floors  80  lb.  per  sq.  ft. ;  and  live  load  on  floors 
100  lb.  per  sq.  ft.  Fig.  9  represents  the  floor  framing  for  a  typical 
panel.  The  weight  of  steel  in  one  panel  is  estimated  as  follows: 
4  Is  12"X31ilb.X20'-0"  2520  lb. 

1  Is  20"  X 80  lb.  X 20'-0"  1600  lb. 
6     Standard  beam  connections,  for  12"  Is  @  20  lb.         120  lb. 

2  Connections  to  columns,  for  12"  Is  @  25  lb.  50  lb. 
2     Connections  to  columns,  for  20"  Is  @  40  lb.  80  lb. 

4    Tie-rods  2"X5'-4"  32  lb- 

4402  lb. 


31 


22 


ESTIMATING 


The  area  of  the  panel  is  20' X  20' =  400  sq.  ft.     The  weight  of  steel 

4402 
in  the  floor  framing  per  sq.  ft.  of  floor  is  —  -^  =  11  pounds,  and  this 

~rvHJ 

multiplied  by  the  total  floor  area  including  roqf,  gives  the  total 
weight  of  floor  framing.     There  are  12  floors  and  a  roof,  so  the  total 

weight  is 

13X100X100X11  =  1,430,000  Ib. 

To  determine  the  weight  of  spandrel  beams,  design  the  typical 
spandrel  and  compute  its  weight  per  lineal  foot,  including  its  con- 
nections. For  this  purpose  only  the  weight  of  wall  is  used  in  design- 
ing the  spandrel,  as  the  material  required  for  the  support  of  the 
floor  adjacent  to  the  wall  has  been  included  in  the  floor  framing. 
In  the  illustration  let  the  panel  length  be 
20  feet,  the  story  height  12  feet,  the  wall 
13  inches  thick  (disregard  openings). 
Then  the  weight  on  the  spandrel  is 
20X12X130  =  31,200  pounds,  which  re- 
quires a  15"  1X42  Ib.  Make  the  con- 
nections as  shown  in  Fig.  10,  using  angles 
6"X4"X|".  Then  the  material  for  one 
spandrel  and  its  connections  is 

1     I  15*  X42  lb.X20'-0*  =840  Ib. 

4     Ls  (6*X4»Xf*)X201b.Xl'-0"   =  80  Ib. 
22     Rivets  @  .3  Ib.  each  =     7  Ib. 


927  Ib. 


927 


The  weight  per  lineal  foot  is  —  =  46.4  pounds,  and  the  total  weight 
of  spandrel  metal  is 

13X400X46.4  =  241,280  Ib. 

If  the  building  will  require  special  wind-bracing  girders,  as 
shown  in  Fig.  8,  they  must  be  estimated  accordingly.  In  some 
instances  it  may  be  well  to  take  several  different  spandrels  at  dif- 
ferent elevations  and  to  take  into  account  different  spandrel  lengths. 

To  get  the  weight  of  the  columns  it  is  necessary  to  know  their 
length  and  average  section.  The  latter  can  be  computed  in  a 
single  item  representing  the  sum  of  the  cross  sections  of  columns 
instead  of  computing  each  column.  To  determine  the  section  it 
is  first  necessary  to  compute  the  loads.  The  assumed  building 


ESTIMATING  23 

is  100'-0"X100'-0"  divided  into  panels  20  feet  square;  has  36 
columns,  and  a  column  length  of  160  feet;  dead  load  on  floors  and 
roof  80  Ib.  per  sq.  ft.;  live  loads  applied  to  the  columns  as  follows: 


LEVEL, 

LIVE  LOAD 

Roof 

25  Ib. 

12th  floor 

85  Ib. 

llth  floor 

80  Ib. 

10th  floor 

75  Ib. 

9th  floor 

70  Ib. 

8th  floor 

65  Ib. 

7th  floor 

GOlb. 

6th  floor 

55  Ib. 

5th  floor 

50  Ib. 

4th  floor 

50  Ib. 

3rd  floor 

50  Ib. 

1st  floor 

75  Ib. 

Total  740  Ib.  per  sq.  ft.  of  building  area; 

walls  13  inches  thick;  no  deduction  for  openings;  columns  and  their 
fireproofing  taken  as  500  Ib.  per  lin.  ft.  .  .  • 

Then  the  total  weight  to  be  supported  by  columns  is  as  follows: 

TOTAL  LOAD  CARRIED 

Dead  load  of  floors  and  roof,  13  X  10,000  X   80     10,400,000  Ib. 
Live  load,  10,000X740       7,400,000  Ib. 

Walls,  400  X 160  X 130       8,320,000  Ib. 

Columns,  36X160X500       2.880,000  Ib. 

29,000,000  Ib. 

Dividing  this  by  12,000  pounds  unit  stress,  gives  an  area  of  2417 
sq.  in.,  which  corresponds  to  a  weight  per  lin.  ft.  of  2417X3.4  = 
8200  pounds.  This  is  the  weight  at  the  bottom  columns.  Assume 
that  the  minimum  or  top  sections  weigh  50  pounds  per  lin.  ft.  each, 
or  a  total  of  36X50  =  1800  pounds.  Then  the  average  weight  of 

8^00  -t- 1 800 
the  column  section  is  —  — — =5000  pounds  per  lin.  ft.  and  the 

total  weight  of  steel  in  the  columns  is 

5000  XI 60  =  800,000  Ib. 
The  total  weight  of  steel  for  this  building  in  round  numbers  is 

Floor  framing        1,430',000  Ib. 
Spandrels  241,000  Ib. 

Columns  800,000  Ib. 

2,471,000  Ib. 


33 


24  ESTIMATING 

The  cubic  contents  of  this  building  is  100  X 100  X 160  =  1,600,000 
cu.  ft.,  and  the  weight  of  steel  per  cu.  ft.  is 

2,471,000 

—  =  l.oo  Ib. 
1,600,000 

The  foregoing  illustration  is  a  very  simple  case.  Ordinarily, 
there  will  be  light  courts,  penthouses,  cornice  or  parapet  framing, 
sidewalks,  several  sizes  of  panels— also  there  may  be  wind  bracing, 
girders  or  trusses  over  large  rooms,  and  chimneys  to  be  included — all 
of  which  can  be  approximated  in  a  similar  manner.  Such  approx- 
imate estimates  cannot  be  expected  to  be  very  accurate.  With 
reasonable  care  they  should  be  within  10  per  cent  of  the  correct 
figures.  They  are  more  likely  to  be  too  low  than  too  high  on  account 
of  miscellaneous  details  that  cannot  be  taken  into  account  except 
by  making  some  additional  allowance  for  them. 

ESTIMATING  COSTS 

The  cost  of  structural  steel  if  analyzed  to  its  origin  would  be 
traced  from  the  iron  mines  to  the  docks,  by  cars  and  boats  to  the 
furnaces,  through  the  smelters,  rolling  mills,  and  structural  shops, 
with  the  intervening  transportation,  and  finally  into  the  structure. 
Each  of  these  items  could  be  divided  into  several  others,  so  it  is 
clear  that  a  great  many  elements  enter  into  the  cost  of  structural 
steel. 

The  engineer  who  is  estimating  the  cost  of  fabricated  structural 
steel  will  not  have  occasion  to  go  back  farther  than  the  rolling  mill, 
beginning  with  the  plain  material  after  it  is  rolled,  cut  to  length, 
and  ready  for  shipment. 

The  items  entering  into  the  cost  are  as  follows:  plain  material 
loaded  on  cars  at  the  mill;  transportation  from  rolling  mill  to 
fabricating  shop;  preparation  of  shop  detail  drawings;  fabrication; 
paint  and  painting;  transportation  from  fabricating  shop  to  site 
of  structure;  erection  and  field  painting;  selling  cost  and  miscella- 
neous items;  and  profit.  The  total  of  these  items  is  the  price  which 
is  to  be  paid  to  the  contractor  by  the  owner  of  the  building.  Each 
item  can  be  analyzed  into  a  number  of  elements  which  are  discussed 
in  the  following  text. 


ESTIMATING  25 

Plain  Material.  It  has  been  the  custom  of  the  trade  for  a  number 
of  years  to  base  the  price  of  plain  structural  steel  on  the  material 
delivered  on  cars  at  Pittsburgh,  Pennsylvania,  so  that  pub- 
lished quotations,  unless  otherwise  stated,  are  understood  to 
be  f.o.b.  (free  on  board)  cars  Pittsburgh.  Of  course  quota- 
tions are  made  f.o.b.  cars  at  other  cities  wherever  the  mills  are 
located,  but  they  are  generally  set  at  such  a  price  that  they 
amount  to  the  Pittsburgh  price  plus  the  freight  from  Pittsburgh 
to  the  point  where  the  quotation  applies.  Thus  when  the  Pitts- 
burgh price  is  1.50  cents  per  pound,  the  Chicago  price  is  1.69 
cents  per  pound.  This  is  not  always  so,  for  there  have  been 
times  when  the  prices  in  Pittsburgh  and  Chicago  have  been  nearly 
or  quite  the  same.  Therefore,  the  estimator  must  keep  informed 
of  changes  in  prices  from  time  to  time  so  that  he  may  know  the 
cheapest  basing  point. 

The  price  of  plain  material  is  made  up  of  the  base  price  and 
extras.  The  base  price  covers  most  of  the  steel  required  for  a 
job,  but  extra  charges  are  made  for  certain  items.  Thus  the  base 
price  applies  to  the  following:  I-beams,  3-inch  to  15-inch  inclusive; 
angles,  3-inch  to  6-inch  inclusive,  |-inch  thick  and  over;  zees,  3-inch 
and  over;  plates,  |-inch  thick  and  over;  and  rods,  f-inch  to  3-inch. 
The  base  price  has  varied  from  $1.10  per  100  pounds  to  $1.70  per 
100  pounds,  f.o.b.  Pittsburgh.  The  proper  figure  to  use  at  any 
time  can  be  obtained  from  the  trade  journals,  or  from  the  dealers. 
It  may  not  be  the  same  for  all  the  standard  sections,  though 
usually  so. 

Extras  are  required  for  the  following  items  and  the  amounts 
given  are  those  usually  charged.  The  seller  may  vary  these  amounts 
from  time  to  time. 

EXTRA 
(per  100  Ib.) 

Beams,  over  15-inch  $0.10 

Angles,  over  6-inch  .  10 

Tees,  3-inch  and  over  .05 

Cutting  to  exact  length  (within  J  inch)  .15 

Rods,  f-inch  and  ££-inch  .05 

Rods,  Hnch  and  j^-inch  .  10 

Special  shapes,  rolled  exclusively  by  one  mill,  are  usually  sold 
at  higher  than  the  base  prices,  as  follows : 


35 


I'll 


ESTIMATING 


SPECIAL  SHAPE  (per 
Light-weight  Carnegie  beams    $0 . 10 

Bethlehem  beams  -05 

Bethlehem  girders  .  10 

Bethlehem  columns  '  -  20 

The  cost  of  a  bill  of  material  f.o.b.  Pittsburgh  may  be  illus- 
trated as  follows: 


MATERIAL 

WEIGHT 

(lb.) 

RATE 
(per  100  lb.) 

COST 

Angles  and  beams,  base  sizes 
Beams,  over  15-inch 
Angles,  over  6-inch 
Bethlehem  column  sections 
Rivet  rods 

422,600 
77,400 
106.000 
362,900 
56,200 

SI.  40 
1.50 
1.50 
1.60 
1.40 

$5,916.40 
1,161.00 
1,590.00 
5,806.40 

786.80 

Total 

1,025,100 

$1.488      ,$15,260.60 

As  the  estimate  of  weight  is  intended  to  represent  the  weight 
of  the  fabricated  material,  some  allowance  must  be  made  for  waste. 
The  waste  material  consists  of  punchings,  corners  cut  from  plates 
and  angles,  and  ends  milled  from  columns.  For  ordinary  building 
work  it  probably  does  not  exceed  2  per  cent  of  the  estimated  weight. 
This,  applied  to  the  average  price  of  material,  computed  above, 
gives  $0.03  per  100  pounds  as  the  rate  to  apply  to  the  total  weight 
to  cover  waste.  In  the  absence  of  more  specific  data,  this  can 
be  adopted  as  an  arbitrary  rate  to  use. 

Transportation  from  Mill  to  Shop.  The  price  of  the  material 
at  the  mill  includes  loading  on  cars;  the  unloading  at  the  fabricating 
plant  is  treated  as  a  part  of  the  fabricating  cost,  so  that  the  trans- 
portation charge  is  for  freight  only.  Usually  the  regular  freight 
tariff  includes  switching  charges  at  both  ends  of  the  route,  but  if 
not,  this  charge  must  be  added.  The  published  tariff  rate  multiplied 
by  the  weight  gives  the  freight  charge. 

The  rates  are  for  carload  shipments,  and  for  less-than-carload 
shipments.  Between  the  mill  and  the  shop  there  is  seldom  occasion 
for  shipping  in  less  than  carload  lots,  as  the  material  for  several 
orders  can  be  combined  if  need  be  to  make  up  carloads.  The 
minimum  carload  is  the  minimum  weight  which  is  required  to 
secure  the  carload  rate.  It  is  an  arbitrary  amount  fixed  as  a  part 
of  the  tariff  by  the  respective  railroads.  It  varies  from  24,000 


ESTIMATING 


27 


pounds  to  40,000  pounds  and  is  subject  to  change  in  the  same 
manner  as  the  rates. 

A  number  of  typical  rates  on  structural  steel  are  given  in  the 
following  schedule.  They  serve  only  for  illustration  and  must  not 
be  used  in  estimating  without  being  confirmed  by  competent 
authority.  Rates  are  given  in  dollars  per  hundred  pounds,  or  in 
cents  per  pound.  Both  the  carload  (c.l.)  rates  and  less-than-carload 
(l.c.l.)  rates  are  listed  from  Pittsburgh. 

Schedule  of  Rates  on  Structural  Steel 


1JEHTINATIOX 

c.  1. 

1.  c.  I. 

Chicago 

$0.189 

$0.221 

New  York 

0.169 

0.201 

Boston 

0.189 

0.221 

Washington 

0.154 

0.186 

Cleveland 

0.105 

0.137 

Louisville 

0.189 

0.221 

New  Orleans 

0.30 

0.37 

St.  Louis 

0.236 

0.273 

Kansas  City 

0.436 

0.513 

Galveston 

0.571 

0.77 

El  Paso 

0.911 

1.402 

St.  Paul 

0.329 

0.431 

Denver 

0.686 

1.071 

Salt  Lake  City 

0.989 

1.793 

Los  Angeles 
San  Francisco        / 

0.80 

1.30 

Seattle 

0.80 

2.20 

Illustrative  Examples.  1.  140,000  pounds  of  steel  are  to  be 
shipped  from  Pittsburgh  to  Kansas  City.  The  c.l.  rate,  as  above, 
is  $0.436  per  100  Ib.  and  the  total  freight  charge  140,000X0.436  = 
$610.40. 

2.  A  shipment  of  structural  steel  is  to  be  made  from  Pitts- 
burgh to  St.  Paul.  Weight  30,000  pounds.  Minimum  carload 
36,000  pounds.  The  freight  at  the  l.c.l.  rate  is  30,000X0.431  = 
$129.30.  But  it  may  be  shipped  as  a  minimum  carload  of  36,000, 
in  which  case  the  freight  charge  is  36,000X0.329  =  $118.44.  From 
this  it  is  clear  that  the  shipment  should  be  billed  as  a  minimum 
carload. 

The  minimum-carload  weight  is  36,000  pounds  over  most 
of  the  United  States  but  is  40,000  pounds  in  the  Rocky  Mountain 


37 


28  ESTIMATING 

g 

States  and  the  Pacific  Coast  States.     Other  amounts  apply  on 
certain  local  lines,  especially  on  narrow-gage  railroads. 

Shop  Detail  Drawings.  Under  this  heading  is  included  the 
clerical  work  of  listing  and  ordering  material  from  the  rolling  mills, 
and  the  drafting  of  the  detail  or  working  drawings.  In  addition 
to  the  actual  labor  chargeable  to  the  specific  job  there  is  also  charge- 
able to  it  a  portion  of  the  general  expense  or  overhead.  This  over- 
head expense  covers  supervision,  supplies,  rent,  heat,  light,  blue 
printing,  etc.  It  is  usually  expressed  in  terms  of  a  percentage 
of  the  direct-labor  cost.  It  varies  and  must  be  adjusted  from  time 
to  time  to  suit  conditions.  A  full  force  with  high  efficiency  gives 
a  low  percentage  for  overhead;  a  small  force  with  little  work  gives 
a  high  percentage. 

Cost  records  of  drawings  may  be  in  terms  of  the  weight,  or 
in  items  of  the  number  of  drawings  required.  If  the  estimate  is 
made  on  the  former  basis,  the  estimator  must  know  the  weight 
of  material  involved  and  the  character  of  the  work,  then  by  com- 
parison with  his  records  he  can  determine  the  proper  figures  to 
apply.  If  the  estimate  is  based  on  the  number  of  drawings,  the 
estimator  must  count  the  number  of  drawings  of  each  class  of  work 
such  as  column,  beam,  girder,  and  miscellaneous  details,  and  apply 
the  rates  which  his  records  indicate  to  be  right  for  the  case  in  hand. 

Actual  data  for  cost  of  detailing  is  not  generally  available, 
being  retained  as  a  part  of  the  working  capital  of  the  office;  further- 
more the  records  of  one  office  may  not  suit  the  conditions  prevailing 
in  another  office.  For  building  work  the  total  cost  of  drawings 
may  vary  from  $1  to  $4  per  ton  of  material.  Probably  SI. 75  or 
$2  per  ton  represents  the  value  of  the  drawings  for  the  structural 
steel  for  an  ordinary  office  building.  Large  tonnage  and  much 
duplication  lead  to  low  cost,  while  irregularity,  little  duplication, 
and  light  material  lead  to  a  high  cost. 

Fabrication.  The  cost  of  fabrication  includes  all  the  expense 
involved  in  converting  the  plain  material  into  the  finished  structural 
members.  The  labor  elements  involved  are  making  templets, 
unloading  steel,  marking,  punching,  assembling,  riveting,  and 
shipping.  In  addition  to  labor  there  is  general  expense  which  must 
cover  templet  lumber,  oil,  fitting  up  bolts,  equipment,  superin- 
tendence, insurance,  taxes,  upkeep  and  depreciation  of  plant,  and 


ESTIMATING 


29 


administration.  The  latter  group  of  items  is  usually  expressed 
in  terms  of  a  percentage  of  the  direct-labor  cost.  This  percentage 
is  a  variable  amount,  depending  upon  the  facilities  of  the  shop, 
the  volume  of  work,  and  character  of  the  work.  For  a  given  shop 
the  general  expense  is  fairly  constant  while  the  labor  cost  may  vary 
greatly  from  month  to  month;  hence  the  percentage  may  need 
to  be  changed  from  month  to  month. 

As  in  the  case  of  drawings  the  detailed  records  of  costs  are 
available  only  to  the  estimators  of  the  company  to  which  they 
belong,  and  due  to  differences  in  equipment  and  other  conditions, 
the  records  of  one  shop  may  not  be  a  safe  criterion  of  the  cost  of 
the  work  in  another  shop. 

In  keeping  cost  records  and  in  estimating  costs,  the  work  is 
classified  in  more  or  less  detail.  The  estimator  generally  uses  the 
total  fabricating  cost  of  each  class  of  material  without  making  an 
analysis  of  the  elements  which  have  been  mentioned.  The  extreme 
and  average  costs  are  approximately  as  tabulated: 


FABRICATION  COSTS 
(per  100  pounds) 

Min. 

Max. 

Avg. 

Beams 
Columns 
Girders 

$0.10 
.40 

.30 

$0.50 

1.50 
.75 

$0.25 
.60 
.50 

In  each  class  the  low  price  applies  to  large  tonnage  of  simple 
workmanship  with  much  duplication;  and  the  high  price  to  small 
tonnage,  complicated  workmanship,  and  little  duplication. 

Paint  and  Painting.  The  cost  of  paint  and  painting  at  the 
shop  may  be  considered  as  a  part  of  the  fabrication,  but  usually 
is  treated  as  a  separate  item. 

The  paints  used  on  steel  are  graphites,  carbons,  iron  oxides, 
red  lead,  and  various  combinations  of  them. 

The  spreading  capacity  may  be  as  high  as  1200  square  feet 
per  gallon  for  the  light  carbon  and  graphite  paints  and  as  low  as 
400  square  feet  for  heavy  red-lead  paint.  For  second-coat  and 
third-coat  work,  most  paints  will  cover  about  20  per  cent  more 
surface  than  for  the  first  coat.  But  if  the  second  and  third  coats 
are  applied  after  erection  the  waste  will  probably  offset  the  added 


39 


30  ESTIMATING 

covering  power.  The  actual  spread  realized  for  a  paint  will  depend 
on  the  smoothness  of  surface,  the  temperature,  and  the  amount  of 
labor  expended  in  applying  it.  For  estimating  purposes  the  spread- 
ing capacity  per  gallon  of  heavy  red  lead  may  be  taken  as  500  square 
feet,  medium-weight  red  lead,  600  square  feet,  iron  oxide  600  square 
feet,  graphite  and  carbon  800  square  feet. 

The  surface  to  be  painted  per  ton  of  steel  depends  on  the  thick- 
ness of  metal.  Metal  1-inch  thick  has  100  square  feet  of  surface 
per  ton;  f-inch  thick  has  400  square  feet.  A  lot  of  I-beams,  ranging 
from  10-inch  to  20-inch  as  required  for  ordinary  floor  framing,  have 
about  200  square  feet  of  surface  per  ton.  Plate  girders  for  building 
framework  will  vary  from  100  to  300  square  feet  per  ton,  and  columns 
from  50  to  200  square  feet.  From  a  set  of  drawings  an  accurate  esti- 
mate can  be  made  if  desired.  Generally,  it  suffices  to  use  an  approxi- 
mate figure.  For  the  ordinary  framework  for  office  buildings  200 
square  feet  of  paint  surface  per  ton  weight  of  steel  is  a  fair  value. 

The  prices  of  paints  range  from  $1  to  $2  per  gallon.  Actual 
prices  must  be  secured  from  dealers  for  the  particular  paint  specified. 

Illustrative  Examples.  1.  Assume  a  carbon  paint  at  SI  per 
gallon,  covering  capacity  800  square  feet,  surface  of  -steel  200  square 
feet  per  ton.  Then  the  quantity  of  paint  required  per  ton  of  steel 
is  I  gallon,  and  its  cost  is  25  cents. 

2.  Assume  a  red-lead  paint  at  $1.85  per  gallon,  covering 
capacity  500  square  feet,  surface  of  steel  200  square  feet  per  ton. 
Then  the  quantity  of  paint  required  per  ton  of  steel  is  f  gallon, 
and  its  value  74  cents. 

The  cost  of  painting  includes  the  direct-labor  cost,  superin- 
tendence, and  such  supplies  as  brushes  and  pails.  The  estimate 
should  be  based  on  the  actual  cost  records  at  the  place  where  the 
work  is  to  be  done.  For  the  carbon  and  graphite  paint  which  are 
easily  applied,  this  cost  may  be  taken  at  25  cents  per  ton.  For 
red-lead  paint  which  is  harder  to  apply  use  50  cents  per  ton,  in 
the  absence  of  more  accurate  data. 

Transportation  from  Fabricating  Shop  to  Building  Site.  The 
freight  rates  on  fabricated  structural  steel  are  the  same  as  for  the 
plain  material,  so  that  the  same  discussion  regarding  transportation 
from  mill  to  shop  applies  also  from  shop  to  site.  However,  there 
are  some  additional  points  to  consider. 


40 


ESTIMATING  31 

It  is  easy  to  make  shipments  in  carloads  of  minimum  weight 
when  the  material  is  straight,  such  as  beams  and  columns,  but  if 
there  are  bulky  items,  such  as  trusses  or  chimneys,  it  may  be  impos- 
sible to  load  up  to  the  minimum  weight,  in  which  case  there  will 
be  excess  freight  to  pay. 

In  most  cases  the  material  must  be  hauled  by  wagon  from  the 
railroad  cars  to  the  site. '  In  the  charge  for  this  hauling  is  included 
the  cost  of  unloading  from  cars  to  wagon  and  from  the  wagons  at 
the  site.  Also  there  may  be  included  the  cost  of  sorting  and  of 
storing,  if  the  material  does  not  arrive  on  the  cars  in  the  order  in 
which  it  is  needed  at  the  building.  With  good  derricks  at  railroad 
and  site,  and  a  short  haul,  the  cost  of  handling  may  be  as  low  as 
50  cents  per  ton.  From  this  it  may  range  upward  to  $2  per  ton. 

The  best  means  of  estimating  the  cost  of  hauling  is  by  securing 
sub-bids  from  teaming  contractors. 

Erection.  The  erection  cost  is  chiefly  labor  cost.  However, 
in  addition  to  the  labor  cost  there  must  be  estimated  wear  and  tear 
on  equipment,  fuel,  power,  and  insurance.  The  labor  cost  may  be 
divided  into  hoisting  and  assembling,  scaffolding  and  false  work, 
and  riveting.  For  the  class  of  buildings  under  consideration  false 
work  is  seldom  required.  If  required  in  considerable  quantity 
it  is  estimated  separately.  The  conditions  which  make  cheap 
erection  are  heavy  members,  large  tonnage,  small  number  of  field 
rivets  per  ton  of  steel.  The  opposite  conditions  of  course  cause 
high  cost. 

The  value  of  erection  varies  from  $6  to  $12  per  ton.  For  the 
ordinary  office  building  it  is  about  $8.  In  the  absence  of  accurate 
data  as  the  basis  for  estimating  a  given  job  it  should  be  submitted 
to  a  sub-contractor  for  a  bid. 

The  foregoing  discussion  and  prices  do  not  include  field  paint 
and  painting.  If  this  is  required,  it  is  estimated  in  the  same  manner 
as  the  shop  painting.  In  general  the  paint  for  the  field  coat  may 
be  figured  at  the  same  cost  per  ton  as  the  shop  paint,  although  the 
quantity  required  is  somewhat  less  if  there  is  little  waste.  The 
labor  cost  of  field  painting  is  from  25  per  cent  to  100  per  cent  more 
than  for  shop  painting. 

Selling  Costs.  Under  this  heading  are  covered  all  expenses 
incidental  to  the  estimating  and  selling  of  the  structural  steel.  It 


41 


32 


ESTIMATING 


ESTIMATE  FOR    General  Contractors 

Name  and  Location    United  Drug  Building,  Chicago,  111. 

Description    Steel-Frame  Building,  40  ft.  x  100  ft. 

15  stories,  2  basements 

Drawing  No.    SI  to  S8  inclusive,  dated  11-28-14 
Plans    Smith  and  Smith,  Archts. 
Specifications    Fmith  &  Smith,  Archts. 
Material    Standard  A.  S.  T.  T. 
Workmanship    Ordinary,  part  of  columns  reamed 
Erection  by    Ourselves 
Haul    2  miles 

Condition  of  Site    Restricted,  co-operate  with  other  trades 
Facilities  for  Storage    None.    Haul  as  needed 
Bid    $93,000  erected,  Chicago 


Date    1-25-15 
Inquiry  No.    C1080 
Sheet  No.    1      of     1 

Anchor  Bolts  furnished  by    None 

Field  Connections  R  iveted    Except  as  noted 

Shop  Painting    One  coat  red  lead,  25c  per  gallon 

Field  Painting    Same,  on  spandrels  only 

Due-Erected    4  months 

Penalty  or  Bonus    None 

Inspection    Mill  and  shop.    Paid  by  owner 

Transportation    Ourselves 


Material 

Price 

.40 
.30 

COST  IN  CENTS  PER  LB. 

1 

2 

3 

4 

5          6 

7 

8       Large  Ls~ 
0"d   Ls 

.40 
30 

Material 

1.30 

1.30 

1.30 

1.30 

1.30     1.30 

1.30 

1.30     Beth.  G. 

1.50 

Shop  Work 
Waste 

.05 
.03 

.10 
.03 

.20 
.03 

.35 
.03 

1.00       .50 
.03       .03 

.70 
.03 

.60     Bars 
.03     U.  M.  PI. 

.30 

Fr'tto    Chicago 

.19 

.19 

.19 

.19 

.19       .19 

.19 

.19     Sh.  PI. 

1.30 

Pin.  R'ds 

Rivets 

Nuts 

Bolts 

Total 

1.57 

1.62 

1.72 

1.87     2.52     2.02 

2.22 

2.12 

SUB-CONTRACTS 

MAIN  CONTRACT 

QUANTITY 

RATE 

AMOUNT 

1     Beams         a 

44,000 

1  57 

691 

2    Ee 

ms 

b 

77,? 

00 

1.62 

1 

,260 

Cast-  Iron  Base  Plates    96,000®  1. 

85   SI, 

"6 

3    Be 

ims 

d 

1,317,, 

(H) 

22 

,661 

4    Be 

ims 

i 

282, 

00 

L87 

I 

,285 

5    Fit 

in:s 

46,' 

00 

2.52 

] 

,177 

6    Co 

umns 

1,038, 

00 

2.02 

21 

,990 

7    Sps 

ndrel  c 

irders 

240, 

00 

2.22 

5 

,330 

8    Chimney 

60,' 

MX) 

2.12 

1,291 

3,158,200 

Draw! 

rs 

.OS 

2 

,527 

Paint, 

ShOT 

.04 

1 

,263 

Paintii 

•.,  sr.op 

.035 

7CO 

Paint, 

field 

320,( 

100 

.04 

128 

Extia 

or  mat 

eri£l 

Lar-e 

F  earns 

and  ,  njes 

418,( 

00 

.10 

418 

Beth.  Girdors 

111,000 

.20 

222 

Cast-iron  Eases 

96,000 

1.85 

1,776 

Net  Cost  Sub-Contracts 

Material  Delivered 
Erection  and  Ptg. 
Hauling 

3,254,200 

2.05 
.42 
.05 

66,809 
13,668 
1,627 

Net  Cost,  Erected 
Selling  Cost  @  5% 

3,254,200 

2.52 

82,104 
4,106 

86,210 

Profit, 

about 

6 

790 

B 

d 

3,254,200 

2.86 

93,000 

Fig.  11.     Form  for  Estimate  Summa 


STATICS. 

This  subject,  called  Statics,  is  a  branch  of  Mechanics.  It 
deals  with  principles  relating  especially  to  forces  which  act  upon 
bodies  at  rest,  and  with  their  useful  applications. 

There  are  two  quite  different  methods  of  carrying  on  the 
discussions  and  computations.  In  one,  the  quantities  under  con- 
sideration are  represented  by  lines  and  the  discussion  is  wholly  by 
means  of  geometrical  figures,  and  computations  are  carried  out  by 
means  of  figures  drawn  to  scale;  this  is  called  the  graphical 
method.  In  the  other,  the  quantities  under  consideration  are 
represented  by  symbols  as  in  ordinary  Algebra  and  Arithmetic, 
and  the  discussions  and  computations  are  carried  on  by  the  methods 
of  those  branches  and  Trigonometry;  this  is  called  the  algebraic 
method.  In  this  paper,  both  methods  are  employed,  and  generally, 
in  a  given  case,  the  more  suitable  of  the  two. 

I.     PRELIMINARY. 

i.  Force.  The  student,  no  doubt,  has  a  reasonably  clear  idea  as 
to  what  is  meant  by  force,  yet  it  may  be  well  to  repeat  here  a  few 
definitions  relative  to  it.  By  force  is  meant  simply  a  push  or 
pull.  Every  force  has  magnitude,  and  to  express  the  magnitude 
of  a  given  force  we  state  how  many  times  greater  it  is  than  some 
standard  force.  Convenient  standards  are  those  of  weight  and 
these  are  almost  always  used  in  this  connection.  Thus  when  we 
speak  of  a  force  of  100  pounds  we  mean  a  force  equal  to  the 
weight  of  100  pounds. 

We  say  that  a  force  has  direction,  and  we  mean  by  this  the 
direction  in  which  the  force  would  move  the  body  upon  which  it 
acts  if  it  acted  alone.  Thus,  Fig.  1  represents  a  body  being 
pulled  to  the  right  by  means  of  a  cord;  the  direction  of  the  force 
exerted  upon  the  body  is  horizontal  and  to  the  right.  The  direc- 
tion  may  be  indicated  by  any  line  drawn  in  the  figure  parallel  to 
the  cord  with  an  arrow  on  it  pointing  to  the  right. 

"We  say  also  that  a  force  has  a  place  of  application,  and  we 
mean  by  that  the  part  or  place  on  the  body  to  which  the  force  is 


45 


4  STATICS 

applied.  When  the  place  of  application  is  small  so  that  it  may  be 
regarded  as  a  point,  it  is  called  the  "  point  of  application."  Thus 
the  place  of  application  of  the  pressure  (push  or  force)  which  a 
locomotive  wheel  exerts  on  the  rail  is  the  part  of  the  surface  of 
the  rail  in  contact  with  the  wheel.  For  practically  all  purposes 
this  pressure  may  be  considered  as  applied  at  a  point  (the  center 
of  the  surface  of  contact),  and  it  is  called  the  point  of  application 
of  the  force  exerted  by  the  wheel  on  the  rail. 

A  force  which  has  a  point  of  application  is  said  to  have  a  line 
of  action,  and  by  this  term  is  meant  the  line  through  the  point  of 
application  of  the  force  parallel  to  its  direction.  Thus,  in  the 
Fig.  1,  the  line  of  action  of  the  force  exerted  on  the  body  is 
the  line  representing  the  string.  Notice  clearly  the  distinction 
between  the  direction  and  line  of  action 
of  the  force;  the  direction  of  the  force  in 

the  illustration  could  be  represented  by 

any  horizontal  line  in  the  figure  with  an 
p.  l  arrowhead  upon  it  pointing  toward  the 

right,  but  the  line  of  action  can  be  rep- 
resented only  by  the  line  representing  the  string,  indefinite  as  to 
length,  but  definite  in  position. 

That  part  of  the  direction  of  a  force  which  is  indicated  by 
means  of  the  arrowhead  on  a  line  is  called  the  sense  of  the  force. 
Thus  the  sense  of  the  force  of  the  preceding  illustration  is  toward 
the  right  and  not  toward  the  left. 

2.  Specification  and  Graphic  Representation  of  a  Force. 
For  the  purposes  of  statics,  a  force  is  completely  specified  or 
described  if  its 

(1)  magnitude,  (2)  line  of  action,  and  (3)  sense  are  known 
or  given. 

These  three  elements  of  a  force  can  be  represented  graphically, 
that  is  by  a  drawing.  Thus,  as  already  explained,  the  straight  line 
(Fig.  1)  represents  the  line  of  action  of  the  force  exerted  upon  the 
body;  an  arrowhead  placed  on  the  line  pointing  toward  the  right 
gives  the  sense  of  the  force;  and  a  definite  length  marked  off  on  the 
line  represents  to  some  scale  the  magnitude  of  the  force.  For  ex- 
ample, if  the  magnitude  is  50  pounds,  then  to  a  scale  of  100  pounds 
to  the  inch,  one-half  of  an  inch  represents  the  magnitude  of  the  force. 


46 


STATICS  5 

It  is  often  convenient,  especially  when  many  forces  are  con- 
cerned in  a  single  problem,  to  use  two  lines  instead  of  one  to 
represent  a  force — one  to  represent  the  magnitude  and  one  the 
line  of  action,  the  arrowhead  being  placed  on  either.  Thus  Fig.  2 
also  represents  the  force  of  the  preceding  example,  AB  (one-half 
inch  long)  representing  the  magnitude  of  the  force  and  db  its  line 
of  action.  The  line  AB  might  have  been  drawn  anywhere  in  the 
figure,  but  its  length  is  definite,  being  fixed  by  the  scale. 

The  part  of  a  drawing  in  which  the  body  upon  which  forces 

act  is  represented,  and  in 
which  the  lines  of  action  of  the 
forces  are  drawn,  is  called  the 
loolbs  space  diagram  (Fig.  2a). 
If  the  body  were  drawn  to 
scale,  the  scale  would  be  a  cer- 
tain number  of  inches  or  feet 

to  the  inch.  The  part  of  a  drawing  in  which  the  force  magnitudes 
are  laid  off  (Fig.  2b)  is  called  by  various  names ;  let  us  call  it  the 
force  diagram.  The  scale  of  a  force  diagram  is  always  a  certain 
number  of  pounds  or  tons  to  the  inch. 

3.  Notation.     AVhen  forces  are  represented  in  two  separate 
diagrams,  it  is  convenient  to  use  a  special  notation,  namely:  a 
capital  letter  at  each  end  of  the  line  representing  the  magnitude 
of  the  force,  and  the  same  small  letters  on  opposite  sides  of  the 
line  representing  the  action  line  of  the  force  (see  Fig.  2).     "When 
we  wish  to  refer  to  a  force,  we  shall  state  the  capital  letters  used 
in   the  notation  of  that  force;  thus  "force  AB"  means  the  force 
whose  magnitude,  action  line,  and  sense  are  represented  by  the 
lines  AB  and  ab. 

In  the  algebraic  work  we  shall  usually  denote  a  force  by  the 
letter  F. 

4.  Scales.     In  this  subject,  scales  will  always  be  expressed 
in  feet  or  pounds  to  an  inch,  or  thus,  1  inch  —  10  feet,  1  inch  = 
100  pounds,  etc.      The  number  of  feet  or  pounds  represented  by 
one  inch  on  the  drawincr  is  called  the  scale  number. 

*D 

To  find  the  length  of  the  line  to  represent  a  certain  distance 
or  force,  divide  the  distance  or  force  by  the  scale  number/  the 
quotient  is  the  length  to  le  laid  off  in  the  drawing.  To  find  the 


47 


6  STATICS 

magnitude  of  a  distance  or  a  force  represented  by  a  certain  line 
in  a  drawing,  multiply  the  length  of  the  line  by  the  scale  num- 
ber; the  product  is  the  magnitude  of  the  distance  or  force,  as  the 
case  may  be. 

The  scale  to  be  used  in  making  drawings  depends,  of  course, 
upon  how  large  the  drawing  is  to  be,  and  upon  the  size  of  the 
quantities  which  must  be  represented.  In  any  case,  it  is  con- 
venient to  select  the  scale  number  so  that  the  quotients  obtained 
by  dividing  the  quantities  to  be  represented  may  be  easily  laid  off 
by  means  of  the  divided  scale  which  is  at  hand. 

Examples.  1.  If  one  has  a  scale  divided  into  32nds,  what 
is  the  convenient  scale  for  representing  40  pounds,  32  pounds,  66 
pounds,  and  70  pounds  ? 

According  to  the  scale,  1  inch  =  32  pounds,  the  lengths 
representing  the  forces  are  respectively  : 

40  32  56  70 

32  =  1*;  32=  1;-g2==1t»   32  =  2fV  inches. 

Since  all  of  these  distances  can  be  easily  laid  off  by  means  of  the 
"  sixteenths  scale,"  1  inch  =  32  pounds  is  convenient. 

2.  What  are  the  forces  represented  by  three  lines,  1.20,  2.11, 
and  0.75  inches  long,  the  scale  being  1  inch  =  200  pounds  ? 

According  to  the  rule  given  in  the  foregoing,  we  multiply 
each  of  the  lengths  by  200,  thus  : 

1.20  X  200  =  240  pounds. 
2.11  X  200  =  422  pounds. 
0.75  X  200  =  150  pounds. 

EXAMPLES  FOR  PRACTICE. 

1.  To  a  scale  of  1  inch  =  500  pounds,  how  long  are  the 
lines  to  represent  forces  of  1,250,  675,  and  900  pounds  ? 

Ans.    2.5, 1.35,  and  1.8  inches 

2.  To  a  scale  of  1  inch  ==  80  pounds,    how  large  are  the 
forces  represented  by  1^  and  1.6  inches  ? 

Ans.  100  and  128  pounds. 

5-  Concurrent  and  Non-concurrent  Forces.  If  the  lines  of 
action  of  several  forces  intersect  in  a  point  they  are  called  concur- 
rent forces,  or  a  concurrent  system,  and  the  point  of  intersection 


48 


STATICS  7 

is  called  the  point  of  concurrence  of  the  forces.  If  the  lines  of 
action  of  several  forces  do  not  intersect  in  the  same  point,  they  are 
called  non -concurrent,  or  a  non-concurrent  system. 

We  shall  deal  only  with  forces  whose  lines  of  action  lie  in  the 
same  plane.  It  is  true  that  one  meets  with  problems  in  which 
there  are  forces  whose  lines  of  action  do  not  lie  in  a  plane,  but 
such  problems  can  usually  be  solved  by  means  of  the  principles 
herein  explained. 

6.  Equilibrium  and  Equilibrant.     When  a  number  of  forces 
act  upon  a  body  which  is  at  rest,  each  tends  to  move  it ;  but  the 
effects  of  all  the  forces  acting  upon  that  body  may  counteract  or 
neutralize  one  another,  and  the  forces  are  said  to  be  balanced  or  in 
equilibrium.     Any  one  of  the  forces   of  a  system  in  equilibrium 
balances  all  the  others.     A  single  force  which  balances  a  number 
of  forces  is  called  the  equilibrant  of  those  forces. 

7.  Resultant  and  Composition.     Any  force  which  would  pro- 
duce the  same  effect  (so  far  as  balancing  other  forces  is  concerned)  as 
that  of  any  system,  is  called  the  resultant  of  that  system.    Evidently 
the  resultant  and  the  equilibrant  of  a  system  of  forces  must  be 
equal  in  magnitude,  opposite  in  sense,  and  act  along  the  same  line. 

The  process  of  determining  the  resultant  of  a  system  of  forces 
is  called  composition. 

8.  Components  and  Resolution.       Any    number    of    forces 
whose  combined  effect  is  the  same  as  that   of  a  single  force  are 
called  components  of  that  force.     The  process  of  determining  the 
components  of  a  force  is  called  resolution.     The  most  important 
case  of  this  is  the  resolution  of  a  force  into  two  components. 

II.  CONCURRENT  FORCES;  COMPOSITION  AND  RESOLUTION. 

9.  Graphical  Composition   of  Two  Concurrent  Forces.     If 

two  forces  are  represented  in  magnitude  and  direction  by  AB 
and  BC  (Fig.  3),  the  magnitude  and  direction  of  their  resultant 
is  represented  by  AC.  This  is  known  as  the  "  triangle  law." 

The  line  of  action  of  the  resultant  is  parallel  to  AC  and 
passes  through  the  point  of  concurrence  of  the  two  given  forces  \ 
thus  the  line  of  action  of  the  resultant  is  ac. 

The  law  can  be  proved  experimentally  by  means  of  two  spring 
balances,  a  drawing  board,  and  a  few  cords  arranged  as  shown  in 


49 


8  STATICS 

Fig.  4.  The  drawing  board  (not  shown)  is  set  up  vertically,  then 
from  two  nails  in  it  the  spring  balances  are  hung,  and  these  in 
turn  support  by  means  of  two  cords  a  small  ring  A  from  which  a 
heavy  body  (not  shown)  is  suspended.  The  ring  A  is  in  equilibrium 
under  the  action  of  three  forces,  a  downward  force  equal  to  the 


Fig.  3. 

weight  of  the  suspended  body,  and  two  forces  exerted  by  the  upper 
cords  whose  values  or  magnitudes  can  be  read  from  the  spring 
balances.  The  first  force  is  the  equilibrant  of  the  other  two. 
Knowing  the  weight  of  the  suspended  body  and  the  readings  of 
the  balances,  lay  off  AB  equal  to  the  pull  of  the  right-hand  upper 
string  according  to  some  convenient  scale,  and  BO  parallel  to  the 


Fig.  4. 

left-hand  upper  string  and  equal  to  the  force  exerted  by  it.  It 
will  then  be  found  that  the  line  joining  A  and  C  is  vertical,  and 
equals  (by  scale)  the  weight  of  the  suspended  body.  Hence  AC, 
with  arrowhead  pointing  down,  represents  the  equilibrant  of  the 
two  upward  pulls  on  the  ring;  and  with  arrowhead  pointing  up,  it 
represents  the  resultant  of  those  two  forces. 


50 


STATICS  9 

Notice  especially  how  the  arrowheads  are  related  in  the  tri- 
angle (Fig.  3),  and  be  certain  that  you  understand  this  lav,  before 
proceeding  far,  as  it  is  the  basis  of  most  of  this  subject. 

Examples.    Fig.  5  represents  a  board  3  feet  square  to  which 
forces  are  applied  as  shown.     It 
is  required  to  compound  or  find  I2oibs. 

the  resultant  of  the  100-  and  80- 
pound  forces. 

First  we  make  a  drawing  of 
the  board  and  mark  upon  it  the 
lines  of  action  of  the  two  forces 
whose  resultant  is  to  be  found,  as 
in  Fig.  6.  Then  by  some  conven- 


8oibs\ 


Toibs.  G 


*» 


Bolbs. 


^rloolbs. 


16o  Ibs. 


ient  scale,  as  100  pounds  to  the  6olbs. 

inch,  lay  off  from  any  convenient  Fig.  5. 

point  A,  a  line  AB  in  the  direc- 
tion of  the  100-pound  force,  and  make  AB  one  inch  long,  repre- 
senting 100  pounds  by  the  scale.     Then  from  B  lay  off  a  line  BC 
in  the  direction  of  the  second  force  and  make  BC,  0.8  of  an  inch 


\8olbs. 


loolbs. 


loolbs. 


Fig.  6. 

long.,  representing  80  pounds  by  the  scale.  Then  the  line  AC,  with 
the  arrow  pointing  from,  A  to  C,  represents  the  magnitude  and 
direction  of  the  resultant.  Since  AC  equals  1.06  inch,  the  result- 
ant equals 

1.06  X  100  =  106  pounds. 

The  line  of  action  of  the  resultant  is  ac,  parallel  to  AC  anl  pass 
ing  through  the  intersection  of  the  lines  of  action  (the  point  of 


51 


10  STATICS 

concurrence)  of  the  given  forces.  To  complete  the  notation,  we 
mark  these  lines  of  action  ab  and  T)C  as  in  the  figure. 

EXAMPLES  FOR  PRACTICE.* 

1.  Determine  the  resultant  of  the  100-  and  the  120-pound 
forces  represented  in  Fig.  5. 

r  The  magnitude  is  188  pounds;  the  force 
Ans.  )  acts  upward  through  A  and  a  point  1.62 
(  feet  to  the  right  of  D. 

2.  Determine  the  resultant  of  the  120-  and  the  160-pound 
forces  represented  in  Fig.  5. 

(  The  magnitude  is  200  pounds;  the  force 
Ans.  <  acts    upward    through    A  and  a  point  9 

(  inches  below  C. 

10.     Algebraic  Composition  of  Two  Concurrent  Forces.       If 
the  angle  between  the  lines  of  action  of  the  two  forces  is  not  90 

decrees,  the  algebraic  method  is 

O  *  O 

not  simple,  and  the  graphical  is 
usually  preferable.  If  the  angle 
is  90  degrees,  the  algebraic  meth- 
od is  usually  the  shorter,  and  this 
is  the  only  case  herein  explained. 
Let  F!  and  F2  be  two  forces 
acting  through  eome  point  of  a 

body  as  represented  in  Fig.  7<z.  AB  and  BC  represent  the  magni- 
tudes and  direction  of  Fl  and  F2  respectively;  then,  according  to 
the  triangle  law  (Art.  9),  AC  represents  the  magnitude  and  direc- 
tion of  the  resultant  of  FA  and  F2,  and  the  line  marked  R  (parallel 
to  AC)  is  the  line  of  action  of  that  resultant.  Since  ABC  is  a 
right  triangle, 


)2  =  (AB/+(BC)' 

•i 
and,  tan  CAB 


*  Use  sheets  of  paper  not  smaller  than  large  letter  size,  and  devote  a  full 
sheet  to  each  example.  In  reading  the  answers  to  these  examples,  remember 
that  the  board  on  which  the  forces  act  was  stated  to  be  3  feet  square. 


o.c; 


STATICS  11 

Now  let  E-  denote  the   resultant.     Since  AC,  AB,  ana  BC 
represent  R,  Fx,  and  F2  respectively,  and  angle  CAB  =.  x, 


R2  =  Fj2  +  F22;  or  R  =  i/jy  + 


22; 


and,  tan  x  —  F2  -f-  Fj. 

By  the  help  of  these  two  equations  we  compute  the  magni- 
tude of  the  resultant  and  inclination  of  its  line  of  action  to  the 
force  Fj. 

Example.  It  is  required  to  determine  the  resultant  of  the 
120-  and  the  160-pound  forces  represented  in  Fig.  5. 

Let  us  call  the  160-pound  force  Ft;  then, 

R  =  V/1602  +  1202  =  1/25,600  +  14,400 
=  ^40,000  =  200  pounds; 

120 
and,        tan  x  —  £-7^  =  |;  hence  x  =  36°  52'. 

The  resultant  therefore  is  200  pounds  in  magnitude,  acts  through 
A  (Fig.  5)  upward  and  to  the  right,  making  an  angle  of  36°  52' 
with  the  horizontal. 

EXAMPLES  FOR  PRACTICE. 

1.  Determine  the  resultant  of  the   50-   and   70-pound  forces 
represented  in  Fig.  5. 

fR  =  86  pounds; 

(  angle  between  R  and  70-pound  force  =  35°  32'. 

2.  Determine  the  resultant  of  the  60-   and  70-pound  forces 
represented  in  Fig  5. 

j  R  =  92.2  pounds  ; 

\  angle  between  R  and  70-pound  force  =^  40°  36'. 
n.  Force  Polygon.  If  lines  representing  the  magnitudes 
and  directions  of  any  number  of  forces  be  drawn  continuous  and 
so  that  the  arrowheads  on  the  lines  point  the  same  way  around  on 
the  series  of  lines,  the  figure  so  formed  is  called  foe  force  polygon 
for  the  forces.  Thus  ABCD  (Fig.  8)  is  a  force  polygon  for  the 
80-,  90-,  and  100-pound  forces  of  Fig.  5,  for  AB,  BC,  and  CD  rep- 
resent the  magnitudes  and  directions  of  those  forces  respectively, 
ar.d  the  arrowheads  point  in  the  same  way  around,  from  A  to  D. 


53 


12  STATICS 

A  number  of  force  polygons  can  be  drawn  for  any  system  of 
forces,  no  two  alike.  Thus  Ax  Bj  Cj  Dx  and  A2  B2  C2  D2  are  other 
force  polygons  for  the  same  three  forces,  80,  90,  and  100  pounds. 
Notice  that  A3  B3  C3  D3  is  not  a  force  polygon  for  the  three  forces 
although  the  lines  represent  the  three  forces  in  magnitude  and 
direction.  The  reason  why  it  is  not  a  force  polygon  is  that  the 
arrowheads  do  not  all  point  the  same  way  around. 


r 


Fig.  8. 

A  force  polygon  is  not  necessarily  a  closed  figure.  If  a  force 
polygon  closes  for  a  system  of  concurrent  forces,  then  evidently 
the  resultant  equals  zero. 

EXAMPLE  FOR  PRACTICE. 

Draw  to  the  same  scale  as  many  different  force  polygons  as 
you  can  for  the  100-,  120-  and  160-pound  forces  of  Fig.  5.  Bear 
in  mind  that  the  arrowheads  on  a  force  polygon  point  the  same 
way  around. 

12.  Composition  of  More  Than  Two  Concurrent  Forces.  The 
graphical  is  much  the  simpler  method;  therefore  the  algebraic  one 
will  not  be  explained.  The  following  is  a  rule  for  performing  the 
composition  graphically: 

(1).     Draw  a  force  polygon  for  the  given  forces. 

(2).  Join  the  two  ends  of  the  polygon  and  place  an  arrow- 
head on  the  joining  line  pointing  from  the  beginning  to  the  end 
of  the  polygon.  That  line  then  represents  the  magnitude  and 
direction  of  the  resultant. 

(3).  Draw  a  line  through  the  point  of  concurrence  of  the 
given  forces  parallel  to  the  line  drawn  as  directed  in  (2).  This  line 
represents  the  action  line  of  the  resultant. 

Example.  It  is  required  to  determine  the  resultant  of  the 
four  forces  acting  through  the  point  E  (Fig.  5). 


54 


STATICS 


13 


First,  make  a  drawing  of  the  board  and  indicate  the  lines  of 
action  of  the  forces  as  shown  in  Fig.  9,  but  without  lettering. 
Then  to  construct  a  force  polygon,  draw  from  any  convenient  point 
A,  a  line  in  the  direction  of  one  of  the  forces  (the  70-pound  force), 
and  make  AB  equal  to  70  pounds  according  to  the  scale  (70  ~ 
100  =  0.7  inch).  Then  from  JB  draw  a  line  in  the  direction  of 
the  next  force  (80-pound),  and  make  BC  equal  to  0.8  inch,  rep- 
resenting 80  pounds.  Next  draw  a  line  from  C  in  the  direction 
of  the  third  force  (90-pound),  and  make  CD  equal  to  0.9  inch, 
representing  90  pounds.  Finally  draw  a  line  from.  D  in  the  direc- 
tion of  the  last  force,  and  make  DE  equal  to  0.6  inch,  representing 
60  pounds.  The  force  polygon  is  ABCDE,  beginning  at  A  and 
ending  at  E. 

The  second  step  is  to  connect  A  and  E  and  place  an  arrow- 
head on  the  line  pointing  from  A  to  E.  This  represents  the 


folios. 


9olbs. 


Tolbs. 


eoiios. 


Fig.  9. 


Since    AE  =  1.16 


magnitude    and   direction  of    the    resultant, 
inches,  the  resultant  is  a  force  of 

1.16  X  100  =  116  pounds. 

The  third  step  is  to  draw  a  line  ae  through  the  point  of  con- 
currence and  parallel  to  AE.  This  is  the  line  of  action  of  the 
resultant.  (To  complete  the  notation  the  lines  of  action  of  the  70-, 
80-,  90-  and  60-pound  forces  should  be  marked  #5,  Ic,  cd,  and  de 
respectively.) 

That  the  rule  for  composition  is  correct  can  easily  be  proved. 
According  to  the  triangle  law,  AC  (Fig.  9),  with  arrowhead  point- 
ing from  A  to  C,  represents  the  magnitude  and  direction  of  the 


55 


14 


STATICS 


resultant  of  the  70-  and  80-pound  forces.  According  to  the  law, 
AD,  with  arrowhead  pointing  from  A  to  D,  represents  the  magni- 
tude and  direction  of  the  resultant  of  AC  and  the  90-pound  force, 
hence  also  of  the  70-,  80-,  and  90-pound  forces.  According  to  the 
law,  AE  with  arrowhead  pointing  from  A  to  E,  represents  the 
magnitude  and  direction  of  the  resultant  of  AD  and  the  60-pound 
force.  Thus  we  see  that  the  foregoing  rule  and  the  triangle  law 
lead  to  the  same  result,  but  the  application  of  the  rule  is  shorter  as 
in  it  we  do  not  need  the  lines  AC  and  AD. 

EXAMPLES  FOR  PRACTICE. 

1.     Determine  the  resultant  of  the  four  forces  acting  through 
the  point  A  (Fig.  5). 

(  380  pounds  acting  upward  through  A  and  a 


Ans. 


|  point  0.45  feet  below  C. 


ScaJeslIn.-loolbs. 


2.  Determine  the  resultant  of  the  three  forces  acting  at  the 
point  F  (Fig.  5). 

(  155  pounds  acting  upward  through  F  and  a 
An8'  \  point  0.57  feet  to  left  of  C. 

13.  Graphical  Resolution  of  Force  into  Two  Concurrent 
Components.  This  is  performed  by  applying  the  triangle  law 
inversely.  Thus,  if  it  is  required  to  resolve  the  100-pound  force 
of  Fig.  5  into  two  components,  we  draw  first  Fig.  10  (a)  to  show 
the  line  of  action  of  the  force,  and  then  AB.  Fig.  10  (b),  to  represent 
the  magnitude  and  direction.  Then  draw  from  A  and  B  any  two 
lines  which  intersect,  mark  their  intersection  C,  and  place  arrow- 
heads on  AC  and  CB,  pointing  from  A  to  C  and  from  C  to  B.  Also 
draw  two  lines  in  the  space  diagram  parallel  to  AC  and  CB  and  so 
that  they  intersect  on  the  line  of  action  of  the  100-pound  force,  db. 


5G 


STATICS  15 

The  test  of  the  correctness  of  a  solution  like  this  is  to  take 
the  two  components  as  found,  and  find  their  resultant;  if  the 
resultant  thus  found  agrees  in  magnitude,  direction,  and  sense 
with  the  given  force  (originally  resolved),  the  solution  is  correct. 

Notice  that  the  solution  above  given  is  not  definite,  for  the 
lines  drawn  from  A  and  B  were  drawn  at  random.  A  force  may 
therefore  be  resolved  into  two  components  in  many  ways.  If, 
however,  the  components  have  to  satisfy  conditions,  there  may  be 
but  one  solution.  In  the  most  important  case  of  resolution,  the 
lines  of  action  of  the  components  are  given;  this  case  is  definite, 
there  being  but  one  solution,  as  is  shown  in  the  following  example. 

Ewample.  It  is  required  to  resolve  the  100-pound  force 
(Fig.  5)  into  two  components  acting  in  the  lines  AE  and  AB. 

Using  the  space  diagram  of  Fig.  10,  draw  a  line  AB  in  Fig. 
10  (c)  to  represent  the  magnitude  and  direction  of  the  100-pound 
force,  and  then  a  line  from  A  parallel  to  the  line  of  action  of 
either  of  the  components,  and  a  line  from  B  parallel  to  the  other, 
thus  locating  D  (or  D' ) .  Then  AD  and  DB  (or  AD'  and  D'B)  repre- 
sent  the  magnitudes  and  directions  of  the  required  components. 

EXAMPLES  FOR  PRACTICE. 

1.  Resolve  the  160-pound  force  of  Fig.  5  into  components 
which  act  in  AF  and  AE. 

f  The  first  component  equals  238^  pounds,  and  its  sense 
Ans.  I  is  from  A  to  F;  the  second  component  equals  119^ 
(  pounds,  and  its  sense  is  from  E  to  A. 

2.  Resolve  the  50-pound  force  of  Fig.  5  ^into  two  compo- 
nents, acting  in  FA  and  FB. 

(  The  first  component  equals  37.3  pounds,  and  its  sense 
Ans.  <  is  from  A  to  F;  the  second  component  equals  47.0 

(  pounds,  and  its  sense  is  from  B  to  F. 

14.  Algebraic  Resolution  of  a  Force  Into  Two  Components. 
If  the  angle  between  the  lines  of  action  of  the  two  components  is 
not  90  degrees,  the  algebraic  method  is  not  simple  and  the 

O  *  O  -t 

graphical  method  is  usually  preferable.  When  the  angle  is  90 
degrees,  the  algebraic  method  is  usually  the  shorter,  and  this  is  the 
only  case  herein  explained. 

Let  F  (Fig.  11)  be  the  force  to  be  resolved  into  two  compo- 


18  STATICS 

nents  acting  in  the  lines  OX  and  OY.  If  AB  is  drawn  to  repre- 
sent the  magnitude  and  direction  of  F,  and  lines  be  drawn  from 
A  and  B  parallel  to  OX  and  OY,  thus  locating  C,  then  AC  and 
BC  with  arrowheads  as  shown  represent  the  magnitudes  and 
directions  of  the  required  components. 

Now  if  F'  and  F"  represent  the  components  acting  in  OX 
and  OY,  and  x  and  y  denote  the  angles  between  F  and  F',  and  F 
and  F"  respectively,  then  AC  and  BC  represent  F'  and  F",  and  the 
angles  BAC  and  ABC  equal  x  and  y  respectively.  From  the 
right  triangle  ABC  it  follows  that 

F'  =  F  cos  -r,     and  F"  =  F  cos  y. 

If  a  force  is  resolved  into  two   components  whose   lines  of 

action  are  at  right  angles  to 
each  other,  each  is  called  a 
B     rectangular  component  of 

F  ^^\     that  force.    Thus  F' and  F" 

are  rectangular  components 
ofF. 

p.      j  The  foregoing  equations 

show  that  the  rectangular 

component  of  a  force  along  any  line  equals  the  product  of  the 
force  and  the  cosine  of  the  angle  between  the  force  and  the  line. 
They  show  also  that  the  rectangular  component  of  a  force  along 
its  own  line  of  action  equals  the  force,  and  its  rectangular  com- 
ponent at  right  angles  to  the  line  of  action  equals  zero. 

Examples.  1.  A  force  of  120  pounds  makes  an  angle  of 
22  degrees  with  the  horizontal.  What  is  the  value  of  its  compo- 
nent along  the  horizontal  ?  * 

Since  cos  22°  =  0.927,  the  value  of  the  component  equals 
120  X  0.927  =  111.24  pounds. 

2.  What  is  the  value  of  the  component  of  the  90-pound 
force  of  Fig.  5  along  the  vertical  ? 

First  we  must  find  the  value  of  the  angle  which  the  90-pound 
force  of  Fig.  5  makes  with  the  vertical. 

*  When  nothing  is  stated  herein  as  to  whether  a  component  is  rectan- 
gular or  not,  then  rectangular  component  is  meant. 


58 


a* 
si 


1 


STATICS  17 


EG 
Since  tan  EAG  ==  -       =  £,  angle  EAG  =  26°  34'. 


Hence  the  value  of  the  desired  component  equals 

90  X  cos  26°  34'  =  90  X  0.8944  =  80.50  pounds. 

EXAMPLES  FOR  PRACTICE. 

1.  Compute  the  horizontal    and  vertical    components    of  a 
force  of  80  pounds  whose  angle  with  the  horizontal  is  60  degrees 

(40  pounds. 
'    /  69.28  pounds. 

2.  Compute  the  horizontal  and  vertical  components  of  the 
100-pound  force  in  Fig.  5.     What  are  their  senses  ? 

(  89.44  pounds  to  the  right. 
1  44.72  pounds  upwards. 

3.  Compute  the  component  of  the  70-pound  force  in  Fig.  5 
along  the  line  EA.     What  is  the  sense  of  the  component  ? 

Ans.     31.  29  pounds  ;  E  to  A. 

III.     CONCURRENT  FORCES  IN  EQUILIBRIUM. 

15.  Condition  of  Equilibrium  Defined.        By   condition    of 
equilibrium  of  a  system  of  forces  is  meant  a  relation  which  they 
must  fulfill  in  order  that  they  may  be  in  equilibrium  or  a  relation 
which  they  fulfill  when  they  are  in  equilibrium. 

In  order  that  any  system  may  be  in  equilibrium,  or  be 
balanced,  their  equilibrant,  and  hence  their  resultant,  must  be 
zero,  and  this  is  a  condition  of  equilibrium.  If  a  system  is  known 
to  be  in  equilibrium,  then,  since  the  forces  balance  among  them- 
selves, their  equilibrant  and  hence  their  resultant  also  equals  zero. 
This  (the  necessity  of  a  zero  resultant)  is  known  as  the  general 
condition  of  equilibrium  for  it  pertains  to  all  kinds  of  force  sys- 
tems. For  special  kinds  of  systems  there  are  special  conditions, 
some  of  which  are  explained  in  the  following. 

16.  Graphical  Condition  of  Equilibrium.     The  "graphical 
condition  of  equilibrium  "  for  a  system  of  concurrent  forces  is 
that  the  polygon  for  the  forces  must  close.     For  if  the  polygon 
closes,  then  the  resultant  equals  zero  as  was  pointed  out  in  Art  11. 

By  means  of  this  condition  we  can  solve  problems  relating  to 


59 


18 


STATICS 


concurrent  forces  which  are  known  to  be  in  equilibrium.  The 
most  common  and  practically  important  of  these  is  the  following: 
The  forces  of  a  concurrent  system  in  equilibrium  are  all 
known  except  two,  but  the  lines  of  action  of  these  two  are  known; 
it  ia  required  to  determine  their  magnitudes  and  directions.  This 
problem  arises  again  and  again  in  the  '<  analysis  of  trusses  "  (Arts. 
23  to  26)  but  will  be  illustrated  first  in  simpler  cases. 

Example.  1.  Fig.  12  represents  a  body  resting  on  an  in- 
clined plane  being  prevented  from  slipping  down  by  a  rope 
fastened  to  it  as  shown.  It  is  required  to  determine  the  pull  or 
tension  on  the  rope  and  the  pressure  of  the  plane  if  the  body 

weighs  120  pounds  and  the 
surface  of  the  plane  is  per- 
fectly smooth.* 

There  are  three  forces  act- 
ing upon  the  body,  namely, 
its  weight  directly  down- 
wards, the  pull  of  the  rope 
and  the  reaction  or  pressure 
of  the  plane  which,  as  ex 

plained  in  the  footnote,  is  perpendicular  to  the  plane.  We  now 
draw  the  polygon  for  these  forces  making  it  close;  thus  draw  AB 
(1.2  inches  long)  to  represent  the  magnitude  and  direction  of  the 
weight,  120  pounds,  then  from  A  a  line  parallel  to  either  one  of 
the  other  forces,  from  B  a  line  parallel  to  the  third,  and  mark  the 
intersection  of  these  two  lines  C;  then  ABC  A  is  the  polygon.  Since 
the  arrowhead  on  AB  must  point  down  and  since  the  arrowheads 
in  any  force  polygon  must  point  the  same  way  around,  those  on 
BC  and  CA  must  point  as  shown. 

Hence  BC  (0.6  inch,  or  60  pounds)  represents  the  magnitude 
and  direction  of  the  pull  of  the  rope  and  CA  (1.04  inches,  or  104 

*  By  "  a  perfectly  smooth  "  surface  is  meant  one  which  offers  no  resist- 
ance to  the  sliding  of  a  body  upon  it.  Strictly,  there  are  no  such  surfaces,  as 
all  real  surfaces  exert  more  or  less  frictional  resistance.  But  there  are  sur- 
faces which  are  practically  perfectly  smooth.  We  use  perfectly  smooth  sur- 
faces in  some  of  our  illustrations  and  examples  for  the  sake  of  simplicity,  for 
we  thus  avoid  the  force  of  friction,  and  the  reaction  or  force  exerted  by  such 
a  surface  on  a  body  resting  upon  it  is  perpendicular  to  the  surface. 


60 


STATICS 


19 


pounds)  represents  the  magnitude  and  direction  of  the  pressure  of 
the  plane  on  the  body. 

2.  A  body  weighing  200  pounds  is  suspended  from  a  email 
ring  which  is  supported  by  means  of  two  ropes  as  shown  in  Fig. 
13.  It  is  required  to  determine  the  pulls  on  the  two  ropes. 

There  are  three  forces  acting  on  the  ring,  namely  the  down- 


3ca.le-. 
lin.-2oolbs. 


Fig.  13. 

ward  force  equal  to  the  weight  of  the  body  and  the  pulls  of  the 
two  ropes.  Since  the  ring  is  at  rest,  the  three  forces  balance  or 
are  in  equilibrium,  and  hence  their  force  polygon  must  close.  We 
proceed  to  draw  the  polygon  and  in  making  it 
close,  we  shall  determine  the  values  of  the  un- 
known pulls.  Thus,  first  draw  AB  (1  inch  long) 
to  represent  the  magnitude  and  direction  of  the 
known  force,  200  pounds;  the  arrowhead  on  it 
must  point  down.  Then  from  A  a  line  parallel 
to  one  of  the  ropes  and  from  B  a  line  parallel  to 
the  other  and  mark  their  intersection  C.  ABCA 


Fig.  14. 


is  the  polygon  for  the  three  forces,  and  since  in  any  force  polygon 
the  arrows  point  the  same  way  around,  we  place  arrowheads  on 
BC  and  CA  as  shown.  Then  BC  and  CA  represent  the  magnitudes 
and  directions  of  the  pulls  exerted  on  the  ring  by  the  right-  and 
left-hand  ropes  respectively. 

BC  =  0.895  inches  and  represents  179  pounds. 
CA  =  0.725  inches  and  represents  145  pounds. 

The  directions  of  the  pulls  are  evident  in  this  case  and  the  arrow- 
heads are  superfluous,  but  they  are  mentioned  to  show  how  to 


61 


20  STATICS 

place  them  and  what  they  mean  so  that  they  may  be  used  when 
necessary.  To  complete  the  notation,  the  rope  at  the  right  should 
be  marked  Tic  and  the  other  ca. 

EXAHPLES  FOR   PRACTICE. 

1.  Fig.  14  represents  a  body  weighing   800   pounds    sus- 
pended from  a  ring  which  ia  supported  by  two  ropes  as  shown. 
Compute  the  pulls  on  the  ropes. 

j  Pull  in  the  horizontal  rope  =  400  pounds. 
'  (  Pull  in  the  inclined  rope  =  894  pounds. 

2.  Suppose  that  in  Fig.  12  the  rope  supporting  the  body  on 
the  plane  is  so  fastened  that  it  is  horizontal.      Determine  the  pull 
on  the  rope  and  the  pressure  on  the  plane  if  the  inclination  of  the 
plane  to  the  horizontal  is  30  degrees  and  the  body  weighs  120 

pounds. 

Ang   (  Pull  =  68.7  pounds. 

'  1  Pressure  =  138  pounds. 

3.  A  sphere  weighing    400    pounds  rests   in    a    Y-shaped 
trough,    the  sides  of  which  are  inclined  at  60  degrees  with  the 
horizontal.     Compute  the  pressures  on  the  sphere. 

Ans.     400  pounds. 

17.  Algebraic  Conditions  of  Equilibrium.  Imagine  each 
one  of  the  forces  of  a  concurrent  system  in  equilibrium  replaced  by 
its  components  along  two  lines  at  right  angles  to  each  other, 
horizontal  and  vertical  for  example,  through  the  point  of  concur- 
rence. Evidently  the  system  of  components  would  also  be  in 
equilibrium.  Now  since  the  components  act  along  one  of  two 
lines  (horizontal  or  vertical),  all  the  components  along  each  line 
must  balance  among  themselves  for  if  either  set  of  components 
were  not  balanced,  the  body  would  be  moved  along  that  line. 
Hence  we  state  that  the  conditions  of  equilibrium  of  a  system  of 
concurrent  forces  are  that  the  resultants  of  the  two  sets  of  com- 
ponents of  the  forces  along  any  two  lines  at  right  angles  to  each 
other  must  equal  zero. 

If  the  components  acting  in  the  same  direction  along  either  of 
the  two  lines  be  given  the  plus  sign  and  those  acting  in  the  other 
direction,  the  negative  sign,  then  it  follows  from  the  foregoing 
that  the  condition  of  equilibrium  for  a  concurrent  system  is  that 


62 


STATICS  21 

the  algebraic  sums  of  the  components  of  the  forces  along  each  ojr 
two  lines  at  right  angles  to  each  other  must  equal  zero. 

Examples.  1.  It  is  required  to  determine  the  pull  on  the 
rope  and  the  pressure  on  the  plane  in  Example  1,  Art.  16  (Fig.  12), 
it  being  given  that  the  inclination  of  the  plane  to  the  horizontal  is 
30  degrees. 

Let  us  denote  the  pull  of  the  rope  by  Fj  and  the  pressure  of 
the  plane  by  F2.  The  angles  which  these  forces  make  with  the 
horizontal  are  30°  and  60°,  respectively;  hence 

the  horizontal  component  of  Ft  =  ¥1  X  cos  30°  =  0.8660  F4, 
and  "  "  "  "  F2  =  F2  X  cos  60°  =  0.5000  F2; 

also  "  "  "  "  the  weight  =  0. 

The  angles  which  Fj  and  F2  make  with  the  vertical  are  60°  and 
30°  respectively,  hence 

the  vertical  component  of  Fx  =  Fx  X  cos  60°  =  0.5000  Fj, 
and  the  vertical  component  of  F2  =  F2  X  cos  30°  =  0.8660  F2; 
also  the  vertical  component  of  the  weight  =  120. 

Since  the  three  forces  are  in  equilibrium,  the  horizontal  and  the 
vertical  components  are  balanced,  and  hence 

0.866  F!  =  0.5  F2 
and  0.5  F!  +  0.866  F2  =  120. 

From  these  two  equations  Fj  and  F2  may  be  determined;  thus 
from  the  first, 

V         0-866    V         1  7*9  V 

F*  =  ~0^~   F^LTBSF,. 
Substituting  this  value  of  F2  in  the  second  equation  we  have 

0.5  Fj  -f  0.866  X  1.732  ¥l  =  120, 
or  2  F!  =  120; 

120 
hence,  Fx  —  —~  —  =  60  pounds, 

and  F2  =  1.732  X  60  =  103.92  pounds. 

2.  It  is  required  to  determine  the  pulls  in  the  ropes*  of 
Fig.  13  by  the  algebraic  method,  it  being  given  that  the  angles 
which  the  left-  and  right-hand  ropes  make  with  the  ceiling  are 
30  and  70  degrees  respectively  and  the  body  weighs  100  pounds. 


63 


22 


STATICS 


Let  us  denote  the  pulls  in  the  right-  and  left-hand  ropes  by 
F!  and  F2  respectively.     Then 

the  horizontal  component  of  Fx  =  Fj  X  cos  70°  =  0.342  Fj, 
the  horizontal  component  of  F2  =  F2  X  cos  30°  =  0.866  F2, 
the  horizontal  component  of  the  weight  =  0, 
the  vertical  component  of  Fx  =  Fx  X  cos  20°  =  0.9397  Fp 
the  vertical  component  of  F2  =  F2  X  cos  60°  =  0.500  F2, 
and  the  vertical  component  of  the  weight  =  100. 

Now  since  these  three  forces  are  in  equilibrium,  the  horizontal 
and  the  vertical  components  balance;  hence 
0.342    F!  =  0.866  F2 
and  0.9397  Fx  -f  0.5  F2  =  100. 


LJTf 


Fig.  15. 


These  equations  may  be  solved  for  the  unknown  forces;  thus  from 
the  first, 


or 


1 00 
F2  =  Q-TJO  =  34.72  pounds, 


Substituting  this  value  of  Fx  in  the  second  equation,  we  get 

0.9397  X  2.532  F2  +  0.5  F2  =  100, 
2.88  F2  =  100 ; 

hence 

and  F,=  2.532  X  34.72  =  87.91  pounds. 

EXAHPLES  FOR  PRACTICE. 

1.  Solve  Ex.  1,  Art.  16  algebraically.  (First  determine 
the  angle  which  the  inclined  rope  makes  with  the  horizontal;  you 
should  find  it  to  be  63°  26'.) 


STATICS  23 

2.  Solve  Ex.  2,  Art.  16  algebraically. 

3.  Solve  Ex.  3,  Art.  16  algebraically. 

IV.  ANALYSIS  OF  TRUSSES;  "HETHOD  OF  JOINTS." 

18.  Trusses.     A  truss  is  a  frame  work  used  principally  to 
support  loads  as  in  roofs  and  bridges.     Fig.  16,    25,    26  and  27 
represent  several  forms  of  trusses.     The  separate  bars  or  rods,  12, 
23,  etc.  (Fig-  16)  are  called  members  of  the  truss  and  all  the  parts 
immediately  concerned  with  the  connection  of  a  number  of  mem- 
bers at  one  place  constitute  a  joint.     A  "pin  joint"   is  shown  in 
Fig.  15  (a)  and  a  "  riveted  joint  "  in  15  (b). 

19.  Truss  Loads.     The  loads  which  trusses  sustain  may  be 
classified  into  fixed,  or  dead,  and  moving  or  live  loads.     A  fixed, 
or  dead  load,  is  one  whose  place  of  application  is  fixed  with  refer- 
ence to  the  truss,  while  a  moving  or  live  load  is  one  whose  place 
of  application  moves  about  on  the  truss. 

Roof  truss  loads  are  usually  fixed,  and  consist  of  the  weight 
of  the  truss,  roof  covering,  the  snow,  and  the  wind  pressure,  if  any. 
Bridge  truss  loads  are  fixed  and  moving,  the  first  consisting  of  the 
weights  of  the  truss,  the  floor  or  track,  the  snow,  and  the  wind  press- 
ure, and  the  second  of  the  weight  of  the  passing  trains  or  wagons. 

In  this  paper  we  shall  deal  only  with  trusses  sustaining  fixed 
loads,  trusses  sustaining  moving  loads  being  discussed  later. 

Weight  of  Roof  Trusses.  Before  we  can  design  a  truss,  it  is 
necessary  to  make  an  estimate  of  its  own  weight;  the  actual  weight 
can  be  determined  only  after  the  truss  is  designed.  There  are  a 
number  of  formulas  for  computing  the  probable  weight  of  a  truss, 
all  derived  from  the  actual  weights  of  existing  trusses.  If  W 
denotes  the  weight  of  the  truss,  I  the  span  or  distance  between 
supports  in  feet  and  a  the  distance  between  adjacent  trusses  in  feet, 
then  for  steel  trusses 


and  the  weight  of  a  wooden  truss  is  somewhat  less. 

Roof  Covering.  The  beams  extending  between  adjacent 
trusses  to  support  the  roof  are  called  purlins.  On  these  there  are 
sometimes  placed  lighter  beams  called  rafters  which  in  turn  eup- 


65 


24  STATICS 

port  roof  boards  or  "sheathing  "  and  the  other  covering.  Some- 
times the  purlins  are  spaced  closely,  no  rafters  being  used. 

The  following  are  weights  of  roof  materials  in  pounds  per 
square  foot  of  roof  surface: 

Sheathing:     Boards,  3  to  5. 

Shingling:  Tin,  1;  wood  shingles,  2  to  3;  iron,  1  to  3;  slate, 
10;  tiles,  12  to  25. 

Rafters:     1.5  to  3. 

Purlins:     Wood,  1  to  3;  iron,  2  to  4. 

Snow  Loads.  The  weight  of  the  snow  load  that  may  have 
to  be  borne  depends,  of  course,  on  location.  It  is  usually  taken 
from  10  to  30  pounds  per  square  foot  of  area  covered  by  the  roof. 

Wind  Pressure.  Wind  pressure  per  square  foot  depends  on 
the  velocity  of  the  wind  and  the  inclination  of  the  surface  on 


(6) 
(a) 
Fig.  16. 

which  it  blows  to  the  direction  of  the  wind.  A  horizontal  wind 
blowing  at  90  miles  per  hour  *produces  a  pressure  of  about  40 
pounds  per  square  foot  on  a  surface  perpendicular  to  the  wind, 
while  on  surfaces  inclined,  the  pressures  are  as  follows: 

10°  to  horizontal,  15  Ib.  per  sq.  ft.          30°  to  horizontal,  32  Ib.  per  sq.  ft. 

20°  to  horizontal,  24  Ib.  per  sq.  ft.          40°  to  horizontal,  36  Ib.  per  sq.  ft. 

50°-90°  to  horizontal,  40  Ib.  per  sq.  ft. 

The  wind  pressure  on  an  .inclined  surface  is  practically  perpen- 
dicular to  the  surface. 

20.  Computation  of  "Apex  Loads."  The  weight  of  the 
roof  covering  including  rafters  and  purlins  comes  upon  the 
trusses  at  the  points  where  they  support  the  purlins;  likewise  the 

*  For  pressure  per  sq.  ft.  using  other  values  than  90  miles,  use  formula  P  =.004  V2,  where 
P  =pressure  per  sq.  ft.  in  Ib.  and  V  =velocity  of  wind  in  miles  per  hr. 


STATICS  25 

pressure  due  to  wind  and  snow.  Sometimes  all  the  purlins  are 
supported  at  joints;  in  such  cases  the  loads  mentioned  act  upon  the 
truss  at  its  joints.  However,  the  roof,  snow,  and  wind  loads  are 
always  assumed  to  be  applied  to  the  truss  at  the  upper  joints  of 
the  trusses.  This  assumption  is  equivalent  to  neglecting  the  bend- 
ing effect  due  to  the  pressure  of  those  purlins  which  are  not  sup- 
ported at  joints.  This  bending  effect  can  be  computed  separately. 

The  weight  of  the  truss  itself  is  assumed  to  come  upon  the 
truss  at  its  upper  joints;  this,  of  course,  is  not  exactly  correct. 
Most  of  the  weight  does  come  upon  the  upper  joints  for  the  upper 
members  are  much  heavier  than  the  lower  and  the  assumption  is 
in  most  cases  sufficiently  correct. 

Examples.  1.  It  is  required  to  compute  the  apex  loads  for 
the  truss  represented  in  Fig.  16,  it  being  of  steel,  the  roof  such 
that  it  weighs  15  pounds  per  square  foot,  and  the  distance  between 
adjacent  trusses  14  feet. 

The  span  being  42  feet,  the  formula  for  weight  of  tru»« 
(Art.  19)  becomes 

42 
14  X  42  (-gg  +  1)  =  1,575.84  pounds. 

The  length  IT  scales  about  24 J  feet,  hence  the  area  of  roofing 
sustained  by  one  truss  equals 

48|  X  14  =  679  square  feet, 
and  the  weight  of  the  roofing  equals 

679  X  15  =  10,185  pounds. 
The  total  load  equals 

1,575.84  +  10,185  =  11,760.84  pounds. 

Now  this  load  is  to  be  proportioned  among  the  five  upper  joints, 
but  joints  numbered  (1)  and  (7)  sustain  only  one-half  as  much 
load  as  the  others.  Hence  for  joints  (1)  and  (7)  the  loads  equal 

-s-  of  11,760  =  1,470, 

o 

and  for  (2),  (4)  and  (5)  they  equal 

-j-of  11,760  =  2,940  pounds. 


67 


26  STATICS 

As  the  weight  of  the  truss  is  only  estimated,  the  apex  loads  would 
be  taken  as  1,500  and  3,000  pounds  for  convenience. 

2.  It  is  required  to  compute  the  apex  loads  due  to  a  snow 
load  on  the  roof  represented  in  Fig.  16,  the  distance  between  trusses 
being  14  feet. 

The  horizontal  area  covered  by  the  roof  which  is  sustained  by 
one  truss  equals 

42  X  14  =  588  square  feet. 

If  we  assume  the  snow  load  equal  to    10  pounds    per  horizontal 
square  foot,  than  the  total  snow  load  borne  by  one  truss  equals 

588  X  10  =  5,880  pounds. 
This  load  divided  between  the  upper  joints  makes 

-g-  X  5,880  =  735  pounds 
at  joints  (1)  and  (7);  and 

r-  X  5,880  =  1,470  pounds 

at  the  joints  (2),  (4),  and  (5). 

3.  It  is  required  to  compute  the  apex   loads  due    to  wind 
pressure  on  the  truss  represented  in  Fig.  16,  the  distance  between 
trusses  being  14  ft. 

The  inclinati0n  of  the  roof  to  the  horizontal  can  be  found  by 
measuring  the  angle  from  a  scale  drawing  with  a  protractor  or  by 
computing  as  follows  :  The  triangle  346  is  equilateral,  and  hence 
its  angles  equal  60  degrees  and  the  altitude  of  the  triangle  equals 

14  X  sin  60  =  12.12  feet. 
The  tangent  of  the  angle  413  equals 

12  12 

-^  =  0.577, 

and  hence  the  angle  equals  30  degrees. 

According  to  Art.  19, 32  pounds  per  square  foot  is  the  proper 
value  of  the  wind  pressure.  Since  the  wind  blows  only  on  one 
Bide  of  the  roof  at  a  given  time,  the  pressure  sustained  by  one  truss 


68 


STATICS  27 

is  the  wind  pressure  on  one  half  of  the  area  of  the  roof  sustained 
by  one  truss,  that  is 

14  X  24L  X  32  =  10,864  pounds. 

One  half  of  this  pressure  comes  upon  the  truss  at  joint  (2)  and  one 
fourth  at  joints  (1)  and  (4). 

EXAMPLES  FOR  PRACTICE. 

1.  Compute  the  apex  loads   due  to    weight  for  the  truss 
represented  in  Fig.  27  if  the  roofing  weighs  12  pounds  per  square 
foot  and  the  trusses  (steel)  are  12  feet  apart. 

Ans.     As  shown  in  Fig.  27. 

2.  Compute  the  apex  loads  due  to  a  snow  load  of  20  pounds 
per  square  foot  on  the   truss   of  Fig.  25,    the  distance   between 
trusses  being  15  feet. 

(  For  joints  (4)  and  (7),  1,200  pounds. 

Ans.    )  For  joints  (1)  and  (3),  3,600  pounds. 

(  For  joint    (2)  '     ,  4,800  pounds. 

3.  Compute  the  apex  loads  due  to  wind  for  the  truss  of  Fig. 
26,  the  distance  between  trusses  being  15  feet. 

{Pressure  equals  practically  29  pounds  per 
square  foot.  Load  at  joint  (2)  is  4,860  and 
at  joints  (1)  and  (3)  2,430  pounds. 

21.  Stress  in  a  Member.     If  a  truss  is  loaded  only  at  its 
joints,  its  members  are  under  either  tension  or  compression,  but 
the  weight  of  a  member  tends  to  bend  it  also,  unless  it  is  vertical. 
If  purlins  rest  upon  members  between  the  joints,  then   they  also 
bend  these  members.     We  have  therefore  tension   members,  com- 
pression members,  and  members  subjected  to  bending  stress  com- 
bined with  tension  or   compression.     Calling  simple   tension  or 
compression  direct  stress  as  in  "  Strength  of  Materials,"  then  the 
process  of  determining  the  direct  stress  in   the  members  is  called 
"  analyzing  the  truss." 

22.  Forces  at  a  Joint.     By  "  forces  at  a  joint  "  is  meant  all 
the  loads,  weights,  and  reactions  which  are  applied  there  and  the 
forces  which  the  members  exert  upon  it.     These  latter  are  pushes 
for  compression  members  and  pulls  for  tension  members,  in  each 
case  acting  along  the  axis  of  the  member.     Thus,  if  the  horizontal 


69 


28  STATICS 

and  inclined  members  in  Fig.  15  are  in  tension,  they  exert  pulls 
on  the  joint,  and  if  the  vertical  is  a  compression  member,  it  ex- 
erts a  push  on  the  joint  as  indicated.  The  forces  acting  at  a 
joint  are  therefore  concurrent  and  their  lines  of  action  are 
always  known. 

23.  General  Method  of  Procedure.  The  forces  acting  at  a 
joint  constitute  a  system  in  equilibrium,  and  since  the  forces  are 
concurrent  and  their  lines  of  action  are  all  known,  we  can  determine 
the  magnitude  of  two  of  the  forces  if  the  others  are  all  known ;  for 
this  is  the  important  problem  mentioned  in  Art.  16  which  was 
illustrated  there  and  in  Art.  17. 

Accordingly,  after  the  loads  and  reactions  on  a  truss,  which  is 


15oo 


— J 


x>x 

fs 

Scas-le: 
lm.=  6ooo  Ibs. 


to  be  analyzed,  have  been  ascertained*,  we  look  for  a  joint  at  whict 
only  two  members  are  connected  (the  end  joints  are  usually  such). 
Then  we  consider  the  forces  at  that  joint  and  determine  the  two 
unknown  forces  which  the  two  members  exert  upon  it  by  methods 
explained  in  Arts.  16  or  17.  The  forces  so  ascertained  are  the 
direct  stresses,  or  stresses,  as  we  shall  call  them  for  short,  and  they 
are  the  values  of  the  pushes  or  pulls  which  those  'same  members 
exert  upon  the  joints  at  their  other  ends. 

Next  we  look  for  another  joint  at  which  but  two  unknown 
forces  act,  then  determine  these  forces,  and  continue  this  process 
until  the  stress  in  each  member  has  been  ascertained.  "We  explain 
further  by  means  of 

Examples.     1.     It  is  desired  to  determine  the  stresses  in  the 


*  How  to  ascertain  the  values  of  the  reactions  is  explained  in  Art.  37. 
{'or  the  present  their  values  in  any  given  case  are  merely  stated. 


70 


STATICS  29 

members  of  the  steel  truss,  represented  in  Fig.  16,  due  to  its  own 
weight  and  that  of  the  roofing  assumed  to  weigh  12  pounds  per 
square  foot.  The  distance  between  trusses  is  14  feet. 

The  apex  loads  for  this  case  were  computed  in  Example  1, 
Art.  20,  and  are  marked  in  Fig.  16.  Without  computation  it  is 
plain  that  each  reaction  equals  one-half  the  total  load,  that  is,  ^  of 
12,000,  or  6,000  pounds. 

The  forces  at  joint  (1)  are  four  in  number,  namely,  the  left 
reaction  (6,000  pounds),   the  load  applied  there  (1,500  pounds), 
and  the  forces  exerted 
by  members  12  and 
13.    For  clearness,  we 
represent  these  forces 

so  far  as  known  in  Fig.  ^S'  /**£>  3oooltos. 

17  (a);  we  can  deter- 
mine the  two   un- 
known   forces     by  \" 
D 
merely  constructing  a  /^\ 

closed  force   polygon         sc&.le« 
for  all  of  them.     To  Hn.  =  6ooo  llos. 
construct  the  polygon,  Pig.  18. 

we  first  represent  the 

known  forces;  thus  AB  (1  inch  long  with  arrowhead  pointing  up) 
represents  the  reaction  and  BC  (J  inch  long  with  arrowhead  point- 
ing down)  represents  the  load.  Then  from  A  and  C  we  draw  lines 
parallel  to  the  two  unknown  forces  and  mark  their  intersection  D 
(or  D').  Then  the  polygon  is  ABCDA,  and  CD  (1.5  inches  = 
9,000  pounds)  represents  the  force  exerted  by  the  member  12  on 
the  joint  and  DA  (1.3  inches  =  7,800  pounds)  represents  the  force 
exerted  by  the  member  13  on  the  joint.  The  arrowheads  on  BC 
and  CD  must  point  as  shown,  in  order  that  all  may  point  the  same 
way  around,  and  hence  the  force  exerted  by  member  12  acts 
toward  the  joint  and  is  a  push,  and  that  exerted  by  13  acts  away 
from  the  joint  and  is  a  pull.  It  follows  that  12  is  in  compression 
and  13  intension. 

If  D'  be  used,  the  same  results  are  reached,  for  the  polygon  is 
ABCD'A  with  arrowheads  as  shown,  and  it  is  plain  that  CD'  and 
DA  also  D'A  and  CD  are  equal  and  have  the  same  sense.  But  one 


71 


^ 


30  STATICS 

of  these  force  polygons  is  preferable  for  reasons  explained  later. 
Since  13"  is  in  compression,  it  exerts  a  push  (9,000  pounds) 
on  joint  (2)  as  represented  in  Fig.  18  («),  and  since  13  is  in 
tension  it  exerts  a  pull  (7,800  pounds)  on  joint  (3)  as  represented 
in  Fig.  19  (a). 

The  forces  at  joint  (2)  are  four  in  number,    the  load   (3,000 
pounds),  the  force  9,000  pounds,  and  the  force  exerted  upon  it  by 
the  members  24  and  23;  they  are  represented  as  far  as  known  in 
Fig.   18  (a).     We  determine  the  un- 
256o  Ibs.  known  forces  by  constructing  a  closed 

\   /  potygon  f°r  aM  °f  them.     Represent- 

(&j  m  V —  ing  the  known  forces  first,  draw  AB 

78oolfos.  ^5  incheg  long  with  arrowhead  point- 

(b)  .  ing  up)   to  represent  the  9,000  pound 

D  A         force  and  BC  (^  inch  long  with  arrow- 

7"~  head  pointing  down)   to  represent,  the 

Seller  load  of  3,000  pounds.     Next  from  A 

c   lin.=6ooorbs.     an(j  Q  <jraw  Iine8  parallel  to  the  two 
Fig.  19.  unknown  forces  and  mark  their  inter- 

section D;  then  the  force  polygon  is 

ABCDA  and  the  arrowheads  on  CD  and  DA  must  point  as  shown. 
CD  (1.25  inches  =  7,500  pounds)  represents  the  force  exerted  on 
joint  (2)  by  24;  since  it  acts  toward  the  joint  the  force  is  a  push 
and  member  24  is  in  compression.  DA  (0.43  inches  =  2,580 
pounds)  represents  the  force  exerted  on  the  joint  by  member  23; 
since  the  force  acts  toward  the  joint  it  is  a  push  and  the  member 
is  in  compression.  Member  23  therefore  exerts  a  push  on  joint 
(3)  as  shown  in  Fig.  19  (a). 

At  joint  (3)  there  are  four  forces,  7,800  pounds,  2,580 
pounds,  and  the  forces  exerted  on  the  joint  by  members  34  and  36. 
To  determine  these,  construct  the  polygon  for  the  four  forces. 
Thus,  AB  (1.3  inches  long  with  arrowhead  pointing  to  the  left) 
represents  the  7,800-pound  force  and  BC  (0.43  inches  long  with 
arrowheads  pointing  down)  represents  the  2,580-pound  force.  Next 
draw  from  A  and  C  two  lines  parallel  to  the  unknown  forces  and 
mark  their  intersection  D;  then  the  force  polygon  is  ABCDA  and 
the  arrowhead  on  CD  and  DA  must  point  upward  and  to  the  right 
respectively.  CD  (0.43  inches  =  2,580  pounds)  represents  the 


72 


STATICS 


31 


force  exerted  on  the  joint  by  member  34;  since  the  force  acts 
away  from  the  joint  it  is  a  pull  and  the  member  is  in  tension. 
DA  (0.87  inches  =  5,220  pounds)  represents  the  force  exerted 
upon  the  joint  by  the  member  36;  since  the  force  acts  away  from 
the  joint,  it  is  a  pull  and  the  member  is  in  tension. 

We  have  now  determined  the  amount  and  kind  of  stress  in 
members  12,  13~,  23,  24~,  34  and  36".  It  is  evident  that  the  stress 
in  each  of  the  members  on  the  right-hand  side  is  the  same  as  the 


ISoolbs 


(d) 


Fig.  20. 

stress  in  the  corresponding  one  on  the  left-hand  side;  hence  further 
analysis  is  unnecessary. 

2.  It  is  required  to  analyze  the  truss  represented  in  Fig. 
20  («),  the  truss  being  supported  at  the  ends  and  sustaining  two 
loads,  1,800  and  600  pounds,  as  shown.  (For  simplicity  we  as- 
sumed values  of  the  load;  the  lower  one  might  be  a  load  due  to  a 
suspended  body.  We  shall  solve  algebraically.) 

The  right  and  left  reactions  equal  900  and  1,500  pounds  as 
is  shown  in  Example  1,  Page  56.  At  joint  (1)  there  are  three 
forces,  namely,  the  reaction  1,500  pounds  and  the  forces  exerted 
by  members  13  and  14,  which  we  will  denote  by  Ft  and  F2  respect 


73 


32  STATICS 

ively.     The  three  forces  are  represented  in  Fig.  20  (J)  as  far  as 

they  are  known.     These  three  forces  being  in  equilibrium,    their 

horizontal  and  their  vertical  components  balance.     Since  there  are 

but  two  horizontal  components   and  two   vertical  components  it 

follows  that  (for  balance  of  the  components)  Fj  must  act  downward 

and  F2  toward  the  right.     Hence  member  13  pushes  on  the  joint 

and  is  under  compression  while  member  14  pulls  on  the  joint  and 

is  under  tension.     From  the  figure  it  is  plain  that 

the  horizontal  component  of  Ft  =  Fx  cos  53°  8'  =  0.6  Fj*, 

the  horizontal  component  of  F2  =  F2, 

the  vertical  component  of  Yl  =  Fj  cos  36°  52'  =  0.8  F,, 

and  the  vertical  component  of  the  reaction  =  1,500. 

Hence  0.6  ^  =  F2,  and  0.8  Fj  =  1,500; 

or,  Ft  =    \  ^    =  1,875  pounds, 

and  F2  =  0.6  X  1,875  =  1,125  pounds. 

Since  members  14  and  13  are  in  tension  and  compression  respect- 
ively, 14  pulls  on  joint  (4)  as  shown  in  Fig.  20  (c)  and  13  pushes 
on  joint  (3)  as  shown  in  Fig.  20  (d). 

The  forces  acting  at  joint  (4)  are  the  load  600  pounds,  the 
pull  1,125  pounds,  and  the  forces  exerted  by  members  34  and  24; 
the  last  two  we  will  call  F3  and  F4  respectively.  The  four  forces 
being  horizontal  or  vertical,  it  is  plain  without  computation  that 
for  balance  F4  must  be  a  pull  of  1,125  pounds  and  F3  one  of  600 
pounds.  Since  members  42  and  43  pull  on  the  joint  they  are 
both  in  tension. 

Member  43,  being  in  tension,  pulls  down  on  joint  (3)  as 
shown  in  Fig.  20  (d).  The  other  forces  acting  on  that  joint  are 
the  load  1,800  pounds,  the  push  1,875  pounds,  the  pull  600 
pounds,  and  the  force  exerted  by  member  32  which  we  will  call 
F5.  The  only  one  of  these  forces  having  horizontal  components 
are  1,875  and  F5;  hence  in  order  that  these  two  components  may 
balance,  F5  mustjict  toward  the  left.  F5  is  therefore  a  push 
and  the  member  32  is  under  compression. 

*  The  angles  can  be  computed  from  the  dimensions  of  the  truss:  often 
they  can  be  ascertained  easiest  by  scaling  them  with  a  protractor  from  a 
large  size  drawing  of  the  truss. 


STATICS 


33 


The  horizontal  component  of  1,875  =  1,875  X  cos  53°  8'  =  1,125; 
and    the  horizontal    component    of    F5  =  F5   X   cos  38°  40'   = 
0.7808  F5. 
Hence  0.7808  F5  =  1,125, 

1  125 

or,  F5  ==  -^Qg  a«  1,440  pounds. 

(This  same  truss  is  analyzed  graphically  later.) 

24.  Notation  for  Graphical  Analysis  of  Trusses.  The  nota- 
tion  described  in  Art.  3  can  be  advantageously  systematized  in 
this  connection  as  follows:  Each  triangular  space  in  the  diagram 
of  the  truss  and  the  spaces  between  consecutive  lines  of  action  of 
the  loads  and  reactions  should  be  marked  by  a  s  mall  letter  (see 


Fig.  21  a).  Then  the  two  letters  on 
opposite  sides  of  any  line  serve  to  denote 
that  line  and  the  same  large  letters  are 
used  to  denote  the  force  acting  in  that 
line.  Thus  cd  (Fig.  21  <z)  refers  to  the 
member  12  and  CD  should  be  used  to 
stand  for  the  force  or  stress  in  that 
member. 

25.  Polygon  for  a  Joint.  In  draw- 
ing  the  polygon  for  all  the  forces  at  a 
joint,  it  is  advantageous  to  represent  the 
forces  in  the  order  in  which  they  occur 
about  the  joint.  Evidently  there  are 
always  two  possible  orders  thus  (see  Fig.  20  d)  F5,  600,  1,875,  and 
1,800  is  one  order  around,  and  F5,  1,800,  1,875,  and  600  is  another. 
The  first  is  called  a  clockwise  order  and  the  second  counter-clockwise. 


lin.-6ooolbs. 
Fig.  21. 


75 


34 


STATICS 


A  force  polygon  for  the  forces  at  a  joint  in  which  the  forces  are 
represented  in  either  order  in  which  they  occur  about  the  joint  is 
called  a,  polygon  for  the  joint,  and  it  will  be  called  a  clockwise  or 
counter-clockwise  polygon  according  as  the  order  followed  is  clock- 
wise or  counter-clockwise.  Thus  in  Fig.  17  (b),  ABCDA  is  a 
clockwise  polygon  for  joint  (1).  ABCD'A  is  a  polygon  for  the 


18oo  Ibs. 


forces  at  the  joint;  it  is  not  a  poly- 
gon for  the  joint  because  the  order 
in  which  the  forces  are  represented 
in  that  polygon  is  not  the  same  as 
either  order  in  which  they  occur 
about  the  joint. 

(Draw  the  counter-clockwise 
polygon  for  the  joint  and  compare 
it  with  ABCDA  and  ABCD'A.) 

26.  Stress  Diagrams.  If  the 
polygons  for  all  the  joints  of  a  truss 
are  drawn  separately  as  in  Example 
1,  Art.  23,  the  stress  in  each  mem- 
It  is  possible  to  combine 


Sca.lc: 
lin,=  looolbs. 

Fig.  22. 

ber  will  have  been  represented  twice. 

the  polygons  so  that  it  will  be  unnecessary  to  represent  the  stress 
in  any  one  member  more  than  once,  thus  reducing  the  number 
of  lines  to  be  drawn.  Such  a  combination  of  force  polygons  is 
called  a  stress  diagram. 

Fig  21  (I)  is  a  stress  diagram  for  the  truss  of  Fig.  21  («) 


76 


STATICS  35 

same  as  the  truss  of  Fig.  16.  It  will  be  seen  that  the  part  of  the 
stress  diagram  consisting  of  solid  lines  is  a  combination  of  separate 
polygons  previously  drawn  for  the  joints  on  the  left  half  of  the 
truss  (Figs.  17,  18  and  19.)  It  will  also  be  seen  that  the  polygons 
are  all  clockwise,  but  counter-clockwise  polygons  could  be  com- 
bined into  a  stress  diagram. 

To  Construct  a  Stress  Diagram  for  a  Truss  Under  Given 
Loads. 

•    1.     Determine  the  reactions*. 

2.  Letter  the  truss  diagram  as  explained  in  Art.  24. 

3.  Construct  a  force  polygon  for  all  the  forces  applied  to  the 
truss    (loads  and    reactions)   representing  them   in    the  order  in 
which    they  occur   around  the  truss,  clockwise  or  counter-clock- 
wise.    (The  part  of  this  polygon  representing  the  loads  is  called 
a  load  line.) 

4.  On  the  sides  of  that  polygon,  construct  the  polygons  for 
all  the  joints.     They  must  be  clockwise  or  counter-clockwise  ac- 
cording as  the  polygon  for  the  loads  and  reactions  is  clockwise  or 
counter-clockwise.     (The  first  polygon  for  a  joint  must  be  drawn 
for  one  at  which  but  two  members  are  connected — the  joints  at 
the  supports  are  usually  such.     Then  one  can  draw  in  succession 
the  polygons  for  joints  at  which  there  are  not  more  than  two  un- 
known forces  until  the  stress  diagram  is  completed.) 

Example.  It  is  desired  to  construct  a  stress  diagram  for  the 
truss  represented  in  Fig.  22  («),  it  being  supported  at  its  ends 
and  sustaining  two  loads  of  1,800  and  600  pounds  as  shown. 

The  right  and  left  reactions  are  900  and  1,500  pounds  as  is 
shown  in  Example  1,  Art.  37.  Following  the  foregoing  directions 
we  first  letter  the  truss,  as  shown.  Then,  where  convenient,  draw 
the  polygon  for  all  the  loads  and  reactions,  beginning  with  any 
force,  but  representing  them  in  order  as  previously  directed. 
Thus,  beginning  with  the  1,800-pound  load  and  following  the 
clockwise  order  for  example,  lay  off  a  line  1.8  inch  in  length  rep- 
resenting  1,800  pounds  (scale  1,000  pounds  to  an  inch);  since  the 
line  of  action  of  the  force  is  Jc>,  the  line  is  to  be  marked  BC  and 
B  should  be  placed  at  the  upper  end  of  the  line  for  a  reason  which 


*  As  already  stated,  methods  for  determining  reactions  are  explained  in 
Art.  37;  for  the  present  the  values  of  the  reactions  in  any  example  will  be  given. 


77 


36  STATICS 

will  presently  appear.  The  next  force  to  be  represented  is  the 
riffht  reaction,  900  pounds  ;  hence  from  Cdraw  a  line  upward  and 
0.90  inch  long.  The  line  of  action  of  this  force  being  ce,  the  line 
just  drawn  should  be  marked  CE  and  since  C  is  already  at  the 
lower  end,  we  mark  the  upper  end  E.  (The  reason  for  placing  B 
at  the  upper  end  of  the  first  line  is  now  apparent.)  The  next 
force  to  be  represented  is  the  600-pound  load  ;  therefore  we  draw 
from  E  a  line  downward  and  0.6  inch  long,  and  since  the  line  of 
action  of  that  force  is  ef,  mark  the  lower  end  of  the  line  F.  The 
next  force  to  be  represented  is  the  left  reaction,  1,500  pounds,  hence 
we  draw  a  line  1.5  inches  long  and  upward  from  F.  If  the  lines 
have  been  carefully  laid  off,  the  end  of  the  last  line  should  fall  at 
B,  that  is,  the  polygon  should  close. 

We  are  now  ready  to  draw  polygons  for  the  joints;  we  may 
begin  at  the  right  or  left  end  as  we  please  but  we  should  bear  in 
mind  that  the  polygons  must  be  clockwise  because  the  polygon  for 
the  loads  and  reactions  (BCEFB)  is  such  an  one.  Beginning  at 
the  right  end  for  example,  notice  that  there  are  three  forces  there, 
the  right  reaction,  de  and  dc.  The  right  reaction  is  represented 
by  CE,  hence  from  E  draw  a  line  parallel  to  de  and  from  C  one 
parallel  to  do  and  mark  their  intersection  D.  Then  CEDO  is  the 
clockwise  polygon  for  the  right-hand  joint,  and  since  CE  acts  up, 
the  arrows  on  ED  and  DC  would  point  to  the  left  and  down 
respectively.  It  is  better  to  place  the  arrows  near  the  joint  to 
which  they  refer  than  in  the  stress  diagram ;  this  is  left  to  the  student. 
The  force  exerted  by  member  ed  on  joint  (2)  .being  a  pull,  ed  is 
under  tension,  and  since  ED  measures  1.12  inches,  the  value  of 
that  tension  is  1,120  pounds.  The  force  exerted  by  member  do  on 
joint  (2)  being  a  push,  do  is  under  compression,  and  since  DC 
measures  1.44  inches,  the  value  of  that  compression  is  1,440  pounds. 

The  member  do  being  in  compression,  exerts  a  push  on  the 
joint  (3)  and  the  member  de  being  in  tension,  exerts  a  pull  on  the 
joint  (4).  Next  indicate  this  push  and  pull  by  arrows. 

We  might  now  draw  the  polygon  for  any  one  of  the  remain- 
ing joints,  for  there  are  at  each  but  two  unknown  forces.  "We 
choose  to  draw  the  polygon  for  the  joint  (3).  There  are  four 
forces  acting  there,  namely,  the  1,800-pound  load,  the  push  (1,440 
pounds)  exerted  by  cd,  and  the  forces  exerted  by  members  ad  and 


78 


STATICS 


37 


ab,  unknown  in  amount  and  sense.  Now  the  first  two  of  these 
forces  are  already  represented  in  the  stress  diagram  by  BC  and 
CD,  therefore  we  draw  from  D  a  line  parallel  to  da  and  from  B 
a  line  parallel  to  la  and  mark  their  intersection  A.  Then  BCDAB 
is  the  polygon  for  the  joint,  and  since  the  arrowhead  on  BC  and 
CD  would  point  down  and  up  respectively,  DA  acts  down  and 
AB  up;  hence  place  arrowheads  in  those  directions  on  da  and 
al  near  the  joint  being  considered.  These  arrows  signify  that 
member  da  pulls  on  the  joint  and  la  pushes;  hence  da  is  in  tension 
and  la  in  compression.  Since  DA  and  AB  measure  0.6  and  1.88 
inches  respectively,  the  values 
of  the  tension  and  compression 
are  600  and  1,880  pounds. 

Next  place  arrowheads  on 
al  and  ad  at  joints  (1)  and  (4) 
to  represent  a  push  and  a 
pull  respectively.  There  re- 
mains now  but  one  stress  un-  p;g  23. 
determined,  that  in  af.  It  can 

be  ascertained  by  drawing  the  polygon  for  joint  1  or  4;  let  us  draw 
the  latter.  There  are  four  forces  acting  at  that  joint,  namely,  the 
600-pound  load,  and  the  forces  exerted  by  members  ed,  da,  and  af. 
The  first  three  forces  are  already  represented  in  the  drawing  by  EF, 
DE  and  DA,  and  the  polygon  for  those  three  forces  (not  closed) 
is  ADEF.  The  fourth  force  must  close  the  polygon ,  that  is,  aline 
from  F  parallel  to  «/"must  pass  through  A,  and  if  the  drawing 
has  been  accurately  done,  it  will  pass  through  A.  The  polygon 
for  the  four  forces  then  is  ADEFA,  and  an  arrowhead  placed  on 
FA  ought  to  point  to  the  left,  but  as  before,  place  it  in  the  truss 
diagram  on  «/"near  joint  (4).  The  force  exerted  by  member  af  on 
joint  (4)  being  a  pull,  af  is  under  tension,  and  since  AF  measures 
1.12  inches,  the  value  of  the  tension  is  1,120  pounds. 

Since  af  is  in  tension  it  pulls  on  joint  (1),  hence  we  place  an 
arrowhead  on  «/"near  joint  (I)  to  indicate  that  pull. 

EXAMPLES  FOR  PRACTICE. 

1.  Construct  a  stress  diagram  for  the  truss  of  the  preceding 
Example  (Fig.  22#)  making  all  the  polygons  counter-clockwise, 
and  compare  with  the  stress  diagram  in  Fig.  22. 


STATICS 


2.     Determine  the  stresses  in  the  members  of  the  truss  repre- 
sented in  Fig.  23  due  to  a  single  load  of  2,000  pounds  at  the  peak. 
Stresses  in  12  and  23  =  1,510  pounds, 
Ans.  )  Stresses  in  14  and  43  —  1,930  pounds, 
Stress  in  ^4  =  490  pounds. 


2ooo  Ibs. 


27.  Stress  Records.  When 
making  a  record  of  the  values 
of  the  stresses  as  determined 
in  { n  analysis  of  a  truss,  it  ia 
convenient  to  distinguish  be- 
tween  tension  and  compres- 
sion by  means  of  the  signs 
plus  and  minus.  Custom 
differs  as  to  use  of  the  signs 
for  this  purpose,  but  we  shall 
use  plus  for  tension  and 
minus  for  compression.  Thus 
+  4,560  means  a  tensile  stress 
of  4,560  pounds,  and  -  7,500 
means  a  compressive  stress  of  7,500  pounds. 

The  record  of  the  stresses  as  obtained  in  an  analysis  can  be 
conveniently  made  in  the  form  of  a  table,  as  in  Example  1  follow- 
ing,  or  in  the  truss  diagram  itself,  as  in  Example  2  (Fig.  25). 

As  previously  explained,  the  stress  in  a  member  is  tensile  or 
compressive  according  as  the  member  pulls  or  pushes  on  the  joints 
between  which  it  extends.  If  the  arrowheads  are  placed  on  tee 


(b) 


Fig.  24. 


80 


STATICS  39 

lines  representing  the  members  as  was  explained  in  Example  1  of 
Art.  26  (Fig.  22),  the  two  arrowheads  on  any  member 

point  toward  each  other  ou  tension  members, 
and  from  each  other  on  compression  members. 

If  the  system  of  lettering  explained  in  Art.  24  is  followed  in 
the  analysis  of  a  truss,  and  if  the  first  polygon  (for  the  loads  and 
reactions)  is  drawn  according  to  directions  (Art.  26),  then  the 
system  of  lettering  will  guide  one  in  drawing  the  polygons  for  the 
joints  as  shown  in  the  following  illustrations.  It  must  be  remem- 
bered always  that  any  two  parallel  lines,  one  in  the  truss  and  one 
in  the  stress  diagram,  must  be  designated  by  the  same  two  letters, 
the  first  by  small  letters  on  opposite  sides  of  it,  and  the  second  by 
the  same  capitals  at  its  ends. 

Examples.  1.  It  is  required  to  construct  a  stress  diagram 
for  the  truss  represented  in  Fig.  24  supported  at  its  ends  and 
sustaining  three  loads  of  2,000  pounds  as  shown.  Evidently 
the  reactions  equal  8,000  pounds. 

Following  the  directions  of  Art.  26,  we  letter  the  truss 
diagram,  then  draw  the  polygon  for  the  loads  and  reactions. 
Thus,  to  the  scale  indicated  in  Fig.  24  (5),  AB,  BC,  and  CD  repre- 
sent the  loads  at  joints  (2),  (3)  and  (5)  respectively  and  DE 
and  EA  represent  the  right  and  the  left  reactions  respectively. 
Notice  that  the  polygon  (ABCDEA)  is  a  clockwise  one. 

At  joint  (l)there  are  three  forces,  the  left  reaction  and  the  forces 
exerted  by  the  members  af&ndfe.  Since  the  forces  exerted  by 
these  two  members  must  be  marked  AF  and  EF  we  draw  from  A 
a  line  parallel  to  of  and  from  E  one  parallel  to  ef  and  mark  their 
intersection  F.  Then  EAFE  is  the  polygon  for  joint  (1),  and  since 
EA  acts  up  (see  the  polygon),  AF  acts  down  and  FE  to  the  right. 
We,  therefore,  place  the  proper  arrowheads  on  of  and  fe  near  (1), 
and  record  (see  adjoining  table)  that  the  stresses  in  those  members 
are  compressive  and  tensile  respectively.  Measuring,  we  find  that 
AF  and  FE  equal  6,150  and  5,100  pounds  respectively. 

Member I       af        I       fe        j       be       j       fe        j     ~gh 

Stress I     -  6,150  |    +5,100  |    -  4,100  |    -  1,875  |    +2,720 


Hi 


40 


STATICS 


We  may  next  draw  the  polygon  for  joint  (6)  or  (2)  since  there 
are  but  two  unknown  forces  at  each.  At  joint  (2)  for  instance, 
the  unknown  forces  are  those  exerted  by  fg  and  fy,  and  the 
known  are  the  load  ab  (2,000  pounds)  and  the  force  exerted 


1 2  ooo IbS. 


"  d 


+1725 

(5) 
/«.  i 

+  2875 
e 

(6) 
n 

(4) 


by  af.     Since   the    unknown   forces  \      in.-2oooibs. 

must  be  marked  FG  and  GB,  draw 
from  F  a  line  parallel  to  fg,  from 
B  a  line  parallel  to  fig,  and  mark 
their  intersection  G.  Then  the  poly- 
gon for  the  joint  is  FABGF,  and 
since  AB  acts  down  (see  the  polygon) 
BG  and  GF  act  down  and  up  respec- 
tively. Therefore,  place  the  proper 
arrowheads  on  Ig  and  gf  near  (2),  and 
record  that  the  stresses  in  those  mem- 
bers are  both  compressive.  Measur- 
ing, we  find  that  BG  and  GF  scale 
4,100  and  1,875  pounds  respectively. 
Now  draw  a  polygon  for  joint 
(3)  or  (6)  since  there  are  hat  two  un- 
known forces  at  each  joint.  At  (3) 

for  instance,  the  unkrown  forces  are  those  exerted  by  ch  and  ght 
the  known  forces  being  the  load  (2,000  pounds)  and  the  force  4,100 
pounds,  exerted  by  Ig.  Since  the  unknown  forces  must  be 
marked  CH  and  GH,  draw  from  C  a  line  parallel  to  cA,  from 
G  one  parallel  to  yhy  and  mark  their  intersection  H.  Then 


(fa) 


Pig.  25. 


STATICS 


41 


GBCHG  is  the  polygon  for  the  joint,  and  since  BC  acts  down 
(see  the  polygon;  CH  acts  up  and  HG  down.  Therefore,  place 
the  proper  arrowheads  on  ch  and  Kg  near  (3),  and  record  that  the 
stresses  in  those  members  are  compressive  and  tensile  respectively. 
Measuring,  we  find  that  CH  and  HG  scale  4,100  and  2,720 
pounds  respectively. 

It  is  plain  that  the  stress  in  any  member  on  the  right- 
hand  side  is  the  same  as  that  in  the  corresponding  member  on 
the  left,  hence  it  is  not  necessary  to  construct  the  complete 
stress  diagram. 

2.     It  is  required  to    analyze    the  truss  of    Fig.   25  which 


rests    on  end  supports  and    sustains    three    loads    each  of  2,000 
pounds  as  shown.     Each  member  is  16  feet  long. 

Evidently,    reactions    are    each    3,000    pounds.     Following 
directions  of    Art.  26,    first   letter    the  truss    diagram  and  then 


draw  a  polygon  for  the  loads  and  reactions  representing  them 
in  either  order  in  which  they  occur  about  the  truss.  DCBAED 
is  a  counter-clockwise  polygon,  DC,  CB,  and  BA  representing  the 
loads  at  joints  (1),  (2)  and  (3),  AE  the  left  reaction,  ED  the  right 
reaction. 


83 


42 


STATICS 


The  construction  of  the  polygons  is  carried  out  as  in  the 
preceding  illustration,  and  little  explanation  is  necessary.  The 
polygon  for  joint  (4)  is  AEFA,  EF  (1,725  pounds  tension) 
representing  the  stress  in  <?/and  FA  (3,450  pounds  compression) 
that  in  af.  The  polygon  for  joint  (3)  is  BAFGB,  FG  (1,150 
pounds  tension)  representing  the  stress  in  fg  and  GB  (2,300 
pounds  compression)  that  in  gb.  The  polygon  for  joint  (5) 
ia  GFEIIG,  EH  (2,875  pounds  tension)  representing  the  stress 
in  eh  and  IIG  (1,150  pounds  compression)  that  in  lig. 

Evidently  the  stress  in  any  member  on  the  right  side  of 
the  truss  is  like  that  in  the  corresponding  member  on  the  left, 
therefore  it  is  not  necessary  to  construct  the  remainder  of  the 
stress  diagram. 

EXAHPLES  FOR  PRACTICE. 

1.  Analyze  the  truss  represented  in  Fig.  26,  it  being  sup- 
ported at  its  ends  and  sustaining  three  loads  of  2,000  and  two 
of  1,000  pounds  as  represented. 

STRESS  RECORD. 


Member  

Stress  

12 
-8,950 

23 
-5,600 

14 

+8,000 

45 
+8,000 

24 
+1,000 

25 
-3.350 

35 
+3,000 

2.  Analyze  the  truss  represented  in  Fig.  27,  it  being  sup- 
ported at  its  ends  and  sustaining  five  2,000-pound  loads  and  two 
of  1,000  as  shown. 

STRESS  RECORD. 


Member  . 
Stress  .  .  . 

12 
-  11.200 

23 

-8.900 

34 

-  8.900 

51           52     1     53     1      54 

+  10.0001-  2.200'-  2.0001  +3.600 

56 
+6.000 

28.  Analysis  for  Snow  Loads.  In  some  cases  the  apex 
snow  loads  are  a  definite  fractional  part  of  the  apex  loads  due 
to  the  weights  of  roof  and  truss.  For  instance,  in  Examples  1 
and  2,  Pages  25  and  26,  it  is  shown  that  the  apex  loads  are 
1,500  and  3,000  pounds  due  to  weight  of  roof  and  truss,  and 
735  and  1,470  due  to  snow;  hence  the  snow  loads  are  practi- 
cally equal  to  one-half  of  the  permanent  dead  loads.  It  follows 
that  the  stress  in  any  member  due  to  snow  load  equals 
practically  one-half  of  the  stress  in  that  member  due  to  the 


STATICS 


43 


permanent  dead  load.  The  snow  load  stresses  in  this  case  can 
therefore  bo  obtained  from  the  permanent  load  stresses  and  no 
stress  diagram  for  snow  load  need  be  drawn. 

In  some  cases,  however,  the  apex  loads  due  to  enow  at  the 
various  joints  are  not  the  same  fractional  part  of  the  permanent 
load.  This  is  the  case  if  the  roof  is  not  all  of  the  same  slope, 
as  for  instance  in  Fig.  25  where  a  part  of  the  roof  is  flat. 
In  such  a  case  the  stresses  due  to  the  snow  load  cannot  be 
determined  from  a  stress  diagram  for  the  permanent  dead  load 


Fig.  28. 

but  a  separate  stress  diagram  for  the  snow  load  must  be  drawn. 
Such  diagrams  are  drawn  like  those  for  permanent  dead  load. 
29.  Analysis  for  Wind  Loads.  Stresses  due  to  wind  press- 
ure  cannot  be  computed  from  permanent  load  stresses;  they  can 
be  most  easily  determined  by  means  of  a  stress  diagram.  Since 
wind  pressure  exists  only  on  one  side  of  a  truss  at  a  time,  the 
stresses  in  corresponding  members  on  the  right  and  left  sides  of  a 
truss  are  unequal  and  the  whole  stress  diagram  must  be  drawn  in 
analysis  for  "  wind  stresses."  Moreover,  where  one  end  of  the 


85 


44  STATICS 

truss  rests  on  rollers,  two  stress  diagrams  must  be  drawn  for  a 
complete  analysis,  one  for  wind  blowing  on  the  right  and  one  for 
wind  blowing  on  the  left  (see  Example  2  following). 

Examples.  1.  It  is  required  to  analyze  the  truss  of  Fig. 
16  for  wind  pressure,  the  distance  between  trusses  being  14  feet. 

The  apex  loads  for  this  case  are  computed  in  Example  3, 
Page  26,  to  be  as  represented  in  Fig.  28.  Supposing  both  ends 
of  the  truss  to  be  fastened  to  the  supports,  then  the  reactions  (due 
to  the  wind  alone)  are  parallel  to  the  wind  pressure  and  the  right 
and  left  reactions  equal  3,600  and  7,200  pounds  as  explained  in 
Example  2,  Page  57. 

To  draw  a  clockwise  polygon  for  the  loads  and  reactions,  we 
lay  off  BC,  CF,  and  FF'  to  represent  the  loads  at  joints  (1),  (2), 
and  (4)  respectively;  then  since  there  are  no  loads  at  joints  (5) 
and  (7)  we  mark  the  point  F'  by  C'  and  B'  also;  then  lay  off 
B'A  to  represent  the  reaction  at  the  right  end.  If  the  lengths 
are  laid  off  carefully,  AB  will  represent  the  reaction  at  the  left 
end  and  the  polygon  is  BCFF'C'B'AB. 

At  joint  (1)  there  are  four  forces,  the  reaction,  the  load,  and 
the  two  stresses.  AB  and  BC  represent  the  first  two  forces,  hence 
from  C  draw  a  line  parallel  to  cd  and  from  A  a  line  parallel  to  ad 
and  mark  their  intersection  D.  Then  ABCDA  is  the  polygon  for 
the  joint  and  CD  and  DA  represent  the  two  stresses.  The  former 
is  7,750  pounds  compression  and  the  latter  9,000  pounds  tension. 

At  joint  (2)  there  are  four  forces,  the  stress  in  cd  (7,750 
pounds  compression),  the  load,  and  the  stresses  in  fe  and  ed.  As 
DC  and  CF  represent  the  stress  7,750  and  the  load,  from  F  draw 
a  line  parallel  to  fe  and  from  D  a  line  parallel  to  dey  and  mark 
their  intersection  E.  Then  DCFED  is  the  polygon  for  the  joint  and 
FE  and  ED  represent  the  stresses  infe  and  ed  respectively.  The 
former  is  7,750  pounds  and  the  latter  5,400,  both  compressive. 

At  joint  (3)  there  are  four  forces,  the  stresses  in  ad  (9,000 
pounds),^  (5,400  pounds),  eg  and  ga.  AD  and  DE  represent 
the  first  two  stresses;  hence  from  E  draw  a  line  parallel  to  eg  and 
from  A  a  line  parallel  to  ag  and  mark  their  intersection  G.  Then 
ADEGA  is  the  polygon  for  the  joint  and  EG  and  GA  represent 
the  stresses  in  eg  and  ga  respectively  The  former  is  5,400  and 
the  latter  3,600  pounds,  both  tensile. 


86 


STATICS 


At  joint  (4)  there  are  five  forces,  the  Btresses  in  eg  (5,400 
pounds)  and  ef  (7,750  pounds),  the  load,  and  the  stresses  inyV  and 
eg.  GE,  EF  and  FF'  represent  the  first  three  forces;  hence  draw 
from  F'  a  line  parallel  tof'e'  and  from  G  a  line  parallel  to  e'g  and 
mark  their  intersection  E'.  (The  first  line  passes  through  G,  hence 
E'  falls  at  G).  Then  the  polygon  for  the  joint  is  GEFF'E'G,  and 


31oo  Ibs.  3loo  Ifas. 


62oo  Ibs. 


3loo  Ibs. 


Reaction  wind  left,378o  ITssJ 
•     right.63So  "  t 


31oo  Ibs. 


Resection   for  wind  left, 
955  olios, 


for  wind  right, 
ooSolbs. 


OAB 


Stress  Dia.gra.rn 
for  wind  left. 


(C) 


GDP 


Fig.  29. 


F'E'  (G,250  pounds   compression)    represents    the  stress  in  fe'. 
Since  E'G  =  0,  the  wind  produces  no  stress  in  member  ge'. 

At  joint  (5)  three  members  are  connected  together  and  there 
is  no  load.     The  sides  of  the  polygon  for  the  joint  must  be  parallel 


87 


46  STATICS 

to  the  members  joined  there.  Since  two  of  those  members  are  in 
the  same  straight  line,  two  sides  of  the  polygon  will  be  parallel 
and  it  follows  as  a  consequence  that  the  third  side  must  be  zero. 
Hence  the  stress  in  the  member  e'd'  equals  zero  and  the  stresses 
in/V  and  d'c'  are  equal.  This  result  may  be  explained  slightly 
differently:  Of  the  stresses  in  e'f^  e'd',  and  d'c'  we  know  the  first 
(6,250)  and  it  is  represented  by  E'F'.  Hence  we  draw  from  F'  a 
line  parallel  to  <'<T  and  one  from  E'  parallel  to  d'e  and  mark  their 
intersection  D'.  Then  the  polygon  for  the  joint  is  E'F'C'D'E,' 
C'D'  (6,250  pounds  compression)  representing  the  stress  in  c'd'. 
Since  E'  and  D'  refer  to  the  same  point,  E'D'  scales  zero  and  there 
is  no  stress  in  e'd'. 

The  stress  in  ad'  can  be  determined  in  various  ways.  Since 
at  joint  (6)  there  are  but  two  forces  (the  stresses  in  ge'  and 
e'd'  being  zero),  the  two  forces  must  be  equal  and  opposite  to 
balance.  Hence  the  stress  in  d'a  is  a  tension  and  its  value  is 
3,600  pounds. 

2.  It  is  required  to  analyze  the  truss  represented  in  Fig. 
24  for  wind  pressure,  the  distance  between  trusses  being  15  feet. 

The  length  18"  equals  l/20a  +  142  or 

1/400  +  196  =  24.4  feet. 

Hence  the  area  sustaining  the  wind  pressure  to  be  borne  by  one 
truss  equals  24.4  X  15  =  366  square  feet. 

The  tangent  of  the  angle  which  the  roof  makes  with  the 
horizontal  equals  14  -*-  20  —  0.7;  hence  the  angle  is  practically 
35  degrees.  According  to  Art.  19,  the  wind  pressures  for  elopes 
of  30  and  40  degrees  are  32  and  36  pounds  per  square  foot; 
hence  for  35  degrees  it  is  34  pounds  per  square  foot.  The  total 
wind  pressure  equals,  therefore,  366  X  34  =  12,444,  or  practically 
12,400  pounds. 

The  apex  load  for 

joint  (2)  is  %  of  12,400,  or  6,200  pounds, 
and  for  joints  (1)  and  (3),  \£  of  12,400,  or  3,100  pounds  (see  Fig.  29). 

When  the  wind  blows  from  the  right  the 

load  for  joint  (5)  is  6,200  pounds,  and 
for  joints  (3)  and  (6)  3,100  pounds. 


STATICS 


47 


If  the  left  end  of  the  truss  is  fastened  to  its  support  and 
the  right  rests  on  rollers*,  when  the  wind  blows  on  the  left  side 
the  right  and  left  reactions  equal  3,780  and  9,550  pounds  respec- 
tively and  act  as  shown.  When  the  wind  blows  on  the  right 
side,  the  right  and  left  reactions  equal  6,380  and  8,050  pounds 
and  act  as  shown.  The  computation  of  these  reactions  is  shown  in 
Example  1,  Page  58. 

For  the  wind  on  the  left  side,  OA,  AB,  and  EC  (Fig.  29£) 
represent  the  apex  loads  at  joints  (1),  (2)  and  (3)  respectively  and 
CE  and  EG  represent  the  right  and  left  reactions;  then  the  poly- 
gon (clockwise)  for  the  loads  and  reactions  is  OABCDPEO.  The 
point  C  is  also  marked  D  and  P  because  there  are  no  loads  at 
joints  (5)  and  (6). 

The  polygon  for  joint  (1)  is  EOAFE,  AF  and  FE  represent- 
ing the  stresses  in  afandfe  respectively.  The  values  are  recorded 
in  the  adjoining  table.  Tin  polygon  for  joint  (2)  is  FABGF, 
BG  and  GF  representing  the  stresses  in  T)g  andy</.  The  polygon 
for  joint  (3)  is  GBCHG,  CH  and  HG  representing  the  stresses  in 
ch  and  Jig  respectively.  At  joint  (5)  there  is  no  load  and  two  of 
the  members  connected  there  are -in  the  same  line;  hence  there  is 
no  wind  stress  in  the  third  member  and  the  stresses  in  the  other 
two  members  are  equal.  The  point  H  is  therefore  also  marked  I 
to  make  HI  equal  to  zero.  The  polygon  for  joint  (5)  is  HCDIH. 

STRESS  RECORD. 


Member. 

Stress,  Wind  Left. 

Stress,  Wind  Right. 

Of 

-    8,850 

-  6,300 

fe 

+12,700 

-2,000 

bg 

-  5,600 

-6,300 

fg 

-  7,000 

0 

hg 

+  5,100 

+3,400 

hi 

0 

-7,000 

ch 

-   7,700 

-4,100 

ie 

+  6,400 

+4,400 

di 

-   7,700 

-7,500 

At  joint  (4)  there  are  four  forces,  all  known  except  the  one 
in  ie.  EF,  FG,  and  Gil  represent  the  first  three;  hence  the  line 

*  Rollers  to  allow  for  free  expansion  and  contraction  of  the  truss  would 
not  be  required  for  one  as  short  as  this.  They  are  not  used  generally  unlefas 
the  truss  is  55  feet  or  more  in  length. 


89 


48 


STATICS 


joining  I  and  E  must  represent  the  stress  in  ie.  This  line,  if  the 
drawing  has  been  correctly  and  accurately  made,  is  parallel  to  ie. 

For  wind  on  right  side,  BC,  CD,  and  DP  Fig.  29(c)  represent 
the  loads  at  joints  (3),  (5)  and  (6)  respectively  and  PE  and  EB 
the  right  and  left  reactions;  then  BCDPEB  is  the  polygon  for  the 
loads  and  reactions.  The  point  B  is  also  marked  A  and  O  because 
there  are  no  loads  at  joints  (2)  and  (1). 

The  polygon  for  joint  (6)  is  DPEID,  El  and  ID  representing 
the  stresses  in  ei  and  id  respectively.  The  polygon  for  joint  (5)  is 
CDIHC,  IH,  and  HC  representing  the  stresses  in  ih  and  he  respect- 
ively.  The  polygon  for  joint  (3)  is  BCHGB,  HG,  and  GB  repre- 
senting the  stresses  in  Jig  and  gb  respectively.  The  polygon  for 
joint  (2)  is  BGFAB,  FA  representing  the  stress  in  /a,  and  since 
GF  equals  zero  there  is  no  stress  in  gf. 

At  joint  (1)  there  are  three  forces,  the  left  reaction,  AF  and 
the  stress  in  fe.  This  third  force  must  close  the  polygon,  so  we 


Fig    *>. 

join  F  and  E  and  this  line  represents   the  stress  in  fe.     If  the 
work  has  been  accurately  done,  FE  will  be  parallel  tofe. 

EXAMPLE  FOR   PRACTICE. 

Analyze  the  truss  represented  in  Fig.  26  for  wind  pressure, 
the  distance  between  trusses  being  15  feet.  (See  Ex.  3,  Page  27, 
for  apex  loads.)  Assuming  both  ends  of  the  truss  fastened  to 
the  supports,  the  reactions  are  both  parallel  to  the  wind  pressure 
and  the  reaction  on  the  windward  side  equals  '6,707  pounds  and 
the  other  equals  3,053  pounds. 


90 


STATICS  49 

Ana.  Stress  Record  for  Wind  Left. 


Member. 

Stress. 

12 

-8,500 

U 

+  8,600 

45 

+  8,600 

24 

0 

23 

-  5,000 

25 

-  6,080 

35 

+  2,800 

36 

-  6,080 

56 

0 

57 

+  4,200 

68 

-6,200 

67 

0 

78 

+  4,200 

V.     COMPOSITION  OF  NON-CONCURRENT  FORCES. 

30.     Graphical  Composition.     As  in  composition  of  concurrent 

systems,  we  first  compound  any  two  of  the  forces  by  means  of  the 
Triangle  Law  (Art.  9),  then  compound  the  resultant  of  these  two 
forces  with  the  third,  then  compound  the  resultant  of  the  first 
three  with  the  fourth  and  so  on  until  the  resultant  of  all  has  been 
found.  It  will  be  seen  in  the  illustration  that  the  actual  construc- 
tions are  not  quite  so  simple  as  for  concurrent  forces. 

Example.  It  is  required  to  determine  the  resultant  of  the 
four  forces  (100, 80, 120,  and  60 pounds)  represented  in  Fig.  30  (a). 

If  we  take  the  100-  and  80-pound  forces  first,  and  from  any 
convenient  point  A  lay  off  AB  and  BO  to  represent  the  magni- 
tudes and  directions  of  those  forces,  then  according  to  the  triangle 
law  AC  represents  the  magnitude  and  direction  of  their  resultant 
and  its  line  of  action  is  parallel  to  AC  and  passes  through  the 
point  of  concurrence  of  the  two  forces.  This  line  of  action  should 
be  marked  ac  and  those  of  the  100-  and  80-pound  forces,  ab  and 
be  respectively. 

If  we  take  the  120-pound  force  as  third,  lay  «off  CD  to  repre- 
sent the  magnitude  and  direction  of  that  force;  then  AD  represents 
the  magnitude  and  direction  of  the  resultant  of  AC  and  the  third 
force,  while  the  line  of  action  of  that  resultant  is  parallel  to  AD 
and  passes  through  the  point  of  concurrence  of  the  forces  AC  and 
CD.  That  line  of  action  should  be  marked  ad  and  that  of  the 
third  force  cd. 


91 


-0  STATICS 

It  remains  to  compound  AD  and  the  remaining  one  of  the 
given  forces,  hence  we  lay  off  DE  to  represent  the  magnitude  and 
direction  of  the  fourth  force;  then  AE  represents  the  magnitude 
and  direction  of  the  resultant  of  AD  and  the  fourth  force  (also  of 
the  four  given  forces).  The  line  of  action  of  the  resultant  is 
parallel  to  AE  and  passes  through  the  point  of  concurrence  of  the 
forces  AD  and  DE.  That  line  should  be  marked  ae  and  the  line 
of  action  of  the  fourth  face  de. 

It  is  now  plain  that  the  magnitude  and  direction  of  the  re- 
sultant  is  found  exactly  as  in  the  case  of  concurrent  forces,  but 
finding  the  line  of  action  requires  an  extra  construction. 

31.  When  the  Forces  Are  Parallel  or  Nearly  5o,  the  method 
of  composition  explained  must  be  modified  slightly  because  there 
is  no  intersection  from  which  to  draw  the  line  of  action  of  the  re- 
sultant  of  the  first  two  forces. 

To  make  such  an  intersection  available,  resolve  any  one  of 
the  given  forces  into  two  components  and  imagine  that  force  re- 
placed by  them;  then  find  the  resultant  of  those  components  and 
the  other  given  forces  by  the  methods  explained  in  the  preceding 
article.  Evidently  this  resultant  is  the  resultant  of  the  given  forces. 

Example.  It  is  required  to  find  the  resultant  of  the  four  paral- 
lel forces  (50,  30,  40,  and  60  pounds)  represented  in  Fig.  31  (a). 

Choosing  the  30-pound  force  as  the  one  to  resolve,  lay  off  AB 
to  represent  the  magnitude  and  direct'on  of  that  force  and  mark 
its  line  of  action  ah.  Next  draw  lines  from  A  and  B  intersecting 
at  any  convenient  point  O;  then  as  explained  in  Art.  13,  AO  and 
OB  (direction  from  A  to  O  and  O  to  B)  represent  the  magnitudes 
and  directions  of  two  components  of  the  30-pound  force,  and  the 
lines  of  action  of  those  components  are  parallel  to  AO  and  OB  and 
must  intersect  on  the  line  of  action  of  that  force,  as  at  1.  Draw 
next  two  such  lines  and  mark  them  ao  and  ob  respectively.  Now 
imagine  the  30-pound  force  replaced  by  its  two  components  and 
then  compound  them  with  the  50-,  40-  and  60-pound  forces. 

In  the  composition,  the  second  component  should  be  taken  as 
the  first  force  and  the  first  component  as  the  last.  Choosing  the 
50-pound  force  as  the  second,  lay  off  BC  to  represent  the  magni- 
tude and  direction  of  that  force  and  mark  the  line  of  action  Ic. 
Then  OC  (direction  O  to  C)  represents  the  magnitude  and  direc- 


STATICS 


51 


tion  of  the  resultant  of  OB  and  BC,  and  oc  (parallel  to  OC  and 
passing  through  the  point  of  concurrence  of  the  forces  OB  and 
BC)  is  the  line  of  action. 

Choosing  the  40-pound  force  next,  lay  off  CD  to  represent 
the  magnitude  and  direction  of  that  force  and  mark  its  line  of 
action  cd.  Then  OD  (direction  O  to  D)  represents  the  magnitude 
and  direction  of  the  resultant  of  OC  and  CD,  and  od  (parallel  to 
OD  and  passing  through  the  point  of  concurrence  of  the  forces  OC 
and  CD)  is  the  line  of  action  of  it. 

Next  lay  off  a  line  DE  representing  the  magnitude  and 
direction  of  the  60-pound  force  and  mark  the  line  of  action  de. 
Then  OE  (direction  O  to  E)  represents  the  magnitude  and  direc- 
tion of  the  resultant  of  OD  and  DE,  and  oe  (parallel  to  OE  and 


C]  - 

j! 


Fig.  31. 

passing  through  the  point  of  concurrence  of  the  forces  OD  and 
DE)  is  the  line  of  action  of  it. 

It  remains  now  to  compound  the  last  resultant  (OE)  and  the 
first  component  (AO).  AE  represents  the  magnitude  and  direc- 
tion of  their  resultant,  and  ae  (parallel  to  AE  and  passing  through 
the  point  of  concurrence  of  the  forces  OE  and  AO)  is  the  line  of 
action. 

32.  Definitions  and  Rule  for  Composition.  The  point  O 
(Fig.  31)  is  called  a  pole,  and  the  lines  drawn  to  it  are  called 
rays.  The  lines  oa,  ob,  oc,  etc.,  are  called  strings  and  collectively 
they  are  called  a  string  polygon.  The  string  parallel  to  the  ray 
drawn  to  the  beginning  of  the  force  polygon  (A)  is  called  the  first 
string,  and  the  one  parallel  to  the  ray  drawn  to  the  end  of  the 
force  polygon  is  called  the  last  string. 


52  STATICS 

The  method  of  construction  may  now  be  described  as  follows: 

1.  Draw   a  force  polygon  for  tlie  given  forces.     The  line 
drawn  from  the  beginning  to  the  end  of  the  polygon  represents 
the  magnitude  and  direction  of  the  resultant. 

2.  Select  a  pole,  draw  the  rays  and  then  the  string  polygon. 
The   line  through  the    intersection  of  the  first  and   last   strings 
parallel  to  the  direction  of  the  resultant  is  the  line  of  action  of  the 
resultant.     (In  constructing  the  string  polygon,  observe  carefully 
that  the  two  strings  intersecting  on  the  line  of  action  of  any  one 
of  the  given  forces  are  parallel  to  the  two  rays  which  are  drawn  to 
the  ends  of  the  line  representing  that  force  in  the  force  polygon.) 

EXAMPLES  FOR  PRACTICE; 

1.     Determine  the  resultant  of  the  50-,  70-,  80-  and  120- 
pound  forces  of  Fig.  5. 

.        (  260  pounds  acting  upwards  1.8  and  0.1  feet 
i  to  the  right  of  A  and  D  respectively. 


4olbs.       3o  bs. 


I51bs. 


Fig.  32. 

2.  Determine  the  resultant  of  the  40-,  10-,  30-  and  20. 
pound  forces  of  Fig.  32. 

»        j  80  pounds   acting  down   1§   feet  from   left 
I  end. 

33.  Algebraic  Composition.  The  algebraic  method  of  com- 
position  is  best  adapted  to  parallel  forces  and  is  herein  explained 
only  for  that  case. 

If  the  plus  sign  is  given  to  the  forces  acting  in  one  direction, 
and  the  minus  sign  to  those  acting  in  the  opposite  direction,  the 
magnitude  and  sense  of  the  resultant  is  given  by  the  algebraic  sum 
of  the  forces;  the  magnitude  of  the  resultant  equals  the  value  of  the 
algebraic  sum;  the  direction  of  the  resultant  is  given  by  the  sign  of 
the  sum,  thus  the  resultant  acts  in  the  direction  which  has  been  called 
plus  or  minus  according  as  the  sign  of  the  3uin  is  plus  or  minus. 


94 


STATICS  53 

If,  for  example,  we  call  up  plus  and  down  minus,  the  alge- 
braic sum  of  the  forces  represented  in  Fig.  32  is- 

-  40  +  10  -  30  -  20  +  50  -  15  =  -  45; 

hence  the  resultant  equals  45  pounds  and  acts  downward. 

The  line  of  action  of  the  resultant  is  found  by  means  of  the 
principle  of  moments  which  is  (as  explained  in  "  Strength  of 
Materials  ")  that  the  moment  of  the  resultant  of  any  number  of 
forces  about  any  origin  equals  the  algebraic  sum  of  the  moments 
of  the  forces.  It  follows  from  the  principle  that  the  arm  of  the 
resultant  with  respect  to  any  origin  equals  the  quotient  of  the 
algebraic  sum  of  the  moments  of  the  forces  divided  by  the  result- 
ant; also  the  line  of  action  of  the  resultant  is  on  such  a  side  of  the 
origin  that  the  sign  of  the  moment  of  the  resultant  is  the  same 
as  that  of  the  algebraic  sum  of  the  moments  of  the  given  forces. 

For  example,  choosing  O  as  origin  of  moments  in  Fig.  32, 
the  moments  of  the  forces  taking  them  in  their  order  from  left  to 
right  are 

-  40X5  =  -  200,  +  10x4  =  +  40,  -  30  X  3  =  -  90, 

-  20x1  =  -  20,  -  50x2-  -100,    +  15x3  ==  +45.* 

Hence  the  algebraic  sum  equals 

-  200  +  40  -  90  -  20  -  100  +  45  =  -  325  foot-pounds. 

The  sign  of  the  sum  being  negative,  the  moment  of  the  resultant 
about  O  must  also  be  negative,  and  since  the  resultant  acts  down, 
its  line  of  action  must  be  on  the  left  side  of  O.  Its  actual 
distance  from  O  equals 


EXAMPLES  FOR  PRACTICE. 

1.  Make  a  sketch  representing  five  parallel  forces,  200,  150 
100,  225,  and  75  pounds,  all  acting  in  the  same  direction  and  2 
feet  apart.  Determine  their  resultant. 


*  The  student  is  reminded  that  when  a  force  tends  to  turn  the  body  on 
which  it  acts  in  the  clockwise  direction,  about  the  selected  origin,  its  moment 
is  a  given  a  plus  sign,  and  when  counter-clockwise,  a  minus  sign. 


95 


54 


STATICS 


(  Resultant  =  750   pounds,   and  acts  in  the  same 
Ans.  '  direction  as  the  given  forces  and  4.47  feet  to  the 

(  left  of  the  75-pound  force. 

2.  Solve  the  preceding  example,  supposing  that  the  first 
three  forces  act  in  one  direction  and  the  last  two  in  the  opposite 
direction. 

(  Resultant  =  150  pounds,  and  acts  in  the  same 
Ans.  •]  direction  with  the  first  three  forces  and  16.3  feet 

(  to  the  left  of  the  75-pound  force. 

Two  parallel  forces  acting  in  the  same  direction  can  be  com- 
pounded by  the  methods  explained  in  the  foregoing,  but  it  is 
sometimes  convenient  to  remember  that  the  resultant  equals  the 
sum  of  the  forces,  acts  in  the  same  direction  as  that  of  the  two 
forces  and  between  them  so  that  the  line  of  action  of  the  resultant 
divides  the  distance  between  the  forces  inversely  as  their  magni- 
tudes. For  example,  let  Fj  and  F2  (Fig.  33)  be  two  parallel 
forces.  Then  if  R  denotes  the  resultant  and  a  and  5  its  distances 
to  Fj  and  F2  as  shown  in  the  figure, 


and 

34-  Couples.  Two  parallel  forces  which  are  equal  and  act  in 
opposite  directions  are  called  a  couple.  The  forces  of  a  couple 
cannot  be  compounded,  that  is,  no  single  force  can  produce  the 
same  effect  as  a  couple.  The  perpendicular  distance  between  the 
lines  of  action  of  the  two  forces  is  called  the  arm,  and  the  product 
of  one  of  the  forces  and  the  arm  is  called  the  'moment  of  the 
couple. 

A  plus  or  minus  sign  is  given  to  the  moment  of  a  couple 
according  as  the  couple  turns  or  tends  to  turn  the  body  on  which 
it  acts  in  the  clockwise  or  counter-clockwise  direction. 

VI.     EQUILIBRIUn  OF  NON-CONCURRENT   FORCES. 

3s.  Conditions  of  Equilibrium  of  Non-Concurrent  Forces 
Not  Parallel  may  be  stated  in  various  ways;  let  us  consider  four. 
First:. 

1.    The  algebraic  sums  of  the  components  of  the  forces  along  each  of 
two  lines  at  right  angles  to  each  other  equal  zero. 


96 


STATICS  55 

2.    The  algebraic  sum  of  the  moments  of  the  forces  about  any  origin 
equals  zero. 

Second : 

1.  The  sum  of  the  components  of  the  forces  along  any  line  equals  zero 

2.  The  sums  of  the  moments  of  the  forces  with  respect  to  each  of  two 

origins  equal  zero. 

Third: 

The  sums  of  the  moments  of  the  forces  with  respect  to  each  of  three 
origins  equals  zero. 

Fourth : 

1.  The  algebraic  sum  of  the  moments  of  the  forces  with  respect  to 

some  origin  equals  zero. 

2.  The  force  polygon  for  the  forces  closes. 

It  can  be  shown  that  if  any  one  of  the  foregoing  sets  of  conditions 
are  fulfilled  by  a  system,  its  resultant  equals  zero.  Hence  each  is 
called  a  set  of  conditions  of  equilibrium  for  a  non-concurrent  sys- 
tem of  forces  which  are  not  parallel. 

The  first  three  sets  are  "•  algebraic"  and  the  last  is  "  mixed," 
(1)  of  the  fourth,  being  algebraic  and  (2)  graphical.  There  is  a 
set  of  graphical  conditions  also,  but  some  one  of  those  here  given 
is  usually  preferable  to  a  set  of  wholly  graphical  conditions. 

Like  the  conditions  of  equilibrium  for  concurrent  forces,  they 
are  used  to  answer  questions  arising  in  connection  with  concurrent 
systems  known  to  be  in  equilibrium.  Examples  may  be  found  in 
Art.  37. 

36.  Conditions  of  Equilibrium  for  Parallel  No*  i-Concurrent 
Forces.     Usually  the  most  convenient  set  of  conditions  to  use  is 
one  of  the  following : 

First: 

1.  The  algebraic  sum  of  the  forces  equals  zero,  and 

2.  The  algebraic  sum  of  the  moments  of  the  forces  about  some  origin 

equals  zero. 

Second: 

The  algebraic  sums  of  the  moments  of  the  forces  with  respect  to  each 
of  two  origins  equal  zero. 

37.  Determination  of  Reactions.     The  weight  of  a  truss,  ita 
loads  and  the  supporting  forces  or  reactions  are  balanced  and  con- 
stitute  a  system  in  equilibrium.     After  the  loads  and  weight  are 


97 


56  STATICS 

ascertained,  the  reactions  can  be  determined  by  means  of  condi- 
tions of  equilibrium  stated  in  Arts.  35  and  36. 

The  only  cases  which  can  be  taken  up  here  are  the  following 
common  ones:  (1)  The  truss  is  fastened  to  two  supports  and 
(2)  The  truss  is  fastened  to  one  support  and  simply  rests  on 
rollers  at  the  other. 

Case  (i)  Truss  Fastened  to  Both  Its  Supports.  If  the  loads 
are  all  vertical,  the  reactions  also  are  vertical.  If  the  loads  are 
not  vertical,  we  assume  that  the  reactions  are  parallel  to  the  result- 
ant of  the  loads. 

The  algebraic  is  usually  the  simplest  method  for  determining 
the  reactions  in  this  case,  and  two  moment  equations  should  be 
used.  Just  as  when  finding  reactions  on  beams  we  first  take  mo- 
ments about  the  right  support  to  find  the  left  reaction  and  then 
about  the  left  support  to  find  the  right  reaction.  As  a  check  we 
add  the  reactions  to  see  if  their  sum  equals  the  resultant  load  as  it 
should. 

Examples.  1.  It  is  required  to  determine  the  reactions  on 
the  truss  represented  in  Fig.  20,  it  being  supported  at  its  ends  and 
sustaining  two  vertical  loads  of  1,800  and  600  pounds  as  shown. 

The  two  reactions  are  vertical;  hence  the  system  in 
equilibrium  consists  of  parallel  forces.  Since  the  algebraic  sum 
of  the  momenta  of  all  the  forces  about  any  point  equals  zero,  to 
find  the  left  reaction  we  take  moments  about  the  right  end,  and  to 
find  the  right  reaction  we  take  moments  about  the  left  end.  Thus, 
if  R!  and  R2  denote  the  left-  and  right-reactions  respectively,  then 
taking  moments  about  the  right  end, 

(R,X  24)  -  (1800  X  15)  -  (600  X  15)  =  0, 
or  2411,=  27,000  +  9,000  =  36,000; 

36,000 
hence  Kj  =     ^     =  1,500  pounds. 

Taking  moment  about  the  left  end, 

-  R2X  24  +  1,800  X  9  +  600  X  9=  0. 
or  24R2  =  16,200  +  5,400  =  21,600; 

hence  R2=  900  pounds. 


STATICS  57 

As  a  check,  add  the  reactions  to  see  if  the  sura  equals  that  of 
the  loads  as  should  be  the  case.  (It  will  be  noticed  that  reactions 
on  trusses  and  beams  under  vertical  loads  are  determined  in  the 
same  manner.) 

2.  It  is  required  to  determine  the  reactions  on  the  truss  rep- 
resented in  Fig.  28  due  to  the  wind  pressures  shown  (2,700,  5,400 
and  2,700  pounds),  the  truss  being  fastened  to  both  its  supports. 

The  resultant  of  the  three  loads  is  evidently  a  single  force  of 
10,800  pounds,  acting  as  shown  in  Fig.  34.  The  reactions  are 


Fig.  34. 

parallel  to  this  resultant;  let  Rj  and  R2  denote  the  left  and  right 
reactions  respectively. 

The  line  abo  is  drawn  through  the  point  7  and  perpendicular 
to  the  direction  of  the  wind  pressure;  hence  with  respect  to  the 
right  support  the  arms  of  Rj  and  resultant  wind  pressure  are  ac 
and  I>c,  and  with  respect  to  the  left  support,  the  arms  of  R2  an(^ tne 
resultant  wind  pressure  are  ac  and  ab.  These  different  arms  can 
be  measured  from  a  scale  drawing  of  the  truss  or  be  computed  as 
follows:  The  angle  Yla  equals  the  angle  417,  and  417  was  shown 
to  be  30  degrees  in  Example  3,  Page  26.  Hence 

ab  =  14  cos  30°,  Ic  =  28  cos  30°,  ac  =  42  cos  30°. 


99 


58  STATICS 

Since  the  algebraic  sums  of  the  moments  of  all  the  forces  acting 
on  the  truss  about  the  right  and  left  supports  equal  zero, 

Rx  X  42  cos  30°  =  10,800  X  28  cos  30°, 
and  R2  X  42  cos  30°  =  10,800  X  14  cos  30°. 

From  the  first  equation, 

10,800  X  28 
Rj  =      —  ^2  -  =  7,200  pounds, 

and  from  the  second, 


Adding  the  two  reactions  we  find  that  their  sum  equals  the  load  as 
it  should. 

Case  (2)  One  end  of  the  truss  rests  on  rollers  and  the  other 
is  fixed  to  its  support.  The  reaction  at  the  roller  end  is  always 
vertical,  but  the  direction  of  the  other  is  not  known  at  the  outset 
unless  the  loads  are  all  vertical,  in  which  case  both  reactions  are 
vertical. 

"When  the  loads  are  not  all  vertical,  the  loads  and  the  reactions 
constitute  a  non  -concurrent  non  -parallel  system  and  any  one  of 
the  sets  of  conditions  of  equilibrium  stated  in  Art.  35  may  be 
used  for  determining  the  reactions.  In  general  the  fourth  set  is 
probably  the  simplest.  In  the  first  illustration  we  apply  the  four 
different  sets  for  comparison. 

Examples.  1.  It  is  required  to  compute  the  reactions  on 
the  truss  represented  in  Fig.  29  due  to  the  wind  pressures  shown 
on  the  left  side  (3,100,  6,200  and  3,100  pounds),  the  truss  resting  on 
rollers  at  the  right  end  and  being  fastened  to  its  support  at  the  left. 

(a)  Let  Rj  and  R?  denote  the  left  and  right  reactions.  The 
direction  of  R2  (at  the  roller  end)  is  vertical,  but  the  direction  of 
R!  is  unknown.  Imagine  Rt  resolved  into  and  replaced  by  its 
horizontal  and  vertical  components  and  call  them  Rj'  and  Rj" 
respectively  (see  Fig.  35.)  The  six  forces,  R/,  R/',  Rg  and  the 
three  wind  pressures  are  in  equilibrium,  and  we  may  apply  any 
one  of  the  sets  of  statements  of  equilibrium  for  this  kind  of  a 
system  (see  Art.  35)  to  determine  the  reactions.  If  we  choose  to 
use  the  first  set  we  find, 


100 


STATICS 


59 


resolving  forces  along  a  horizontal  line, 

-  R/  +  3,100  cos  55°  +  6,200  cos  55°  +  3,100  cos  55°  =  0; 
resolving  forces  along  a  vertical  line, 

+  R/'  +  R2  -  3,100  cos  35°  -  6,200  cos  35°  -  3,100  cos  35°  =  0  ; 
taking  moments  about  the  left  end, 

+  6,200  X  12.2  +  3,100  X  24.4  -  R2  X  40  =  0. 
From  the  first     equation, 
K/= 3,100  cos  55°  +  6,200  cos  55° +3,100  cos  55°=  7,113  pounds, 

\31oolbs. 


Fig.  35. 
and  from  the  third, 

6,200  X  12.2  +  3,100  X  24.4 

Ii2  = JQ =  3,782  pounds. 

Substituting  this  value  of  R2  in  the  second  equation  we  find  that 

R,  "  =3,100  cos  35°  +  6,200  cos  35°  +  3,100  coa  35°-  3,782 

=  10,156  -  3,782  =  6,374  pounds. 

If  desired,  the  reaction  Rt  can  now  be  found  by  compounding 
its  two  components  R,'  ai>d  Rj". 


101 


60  STATICS 

(J)     Using  the  second  set  of  conditions  of  equilibrium  stated 
in  Art.  35  we   obtain  the   following  three    "equilibrium  equa- 
tions "  : 
As  in  (1),  resolving  forces  along  the  horizontal  gives 

-R/  +  3,100  cos  55°  +  6,200  cos  55°  +  3,100  cos  55°  =«  0, 
and  taking  moments  about  the  left  end, 

6,200  X  12.2  -f  3,100  X  24.4-R2X  40  =  0. 
Taking  moments  about  the  right  end  gives 

Rx"  X  40-3,100  X  "^6- 6,200  x~£6- 3,100  X~^6  =  0 

Just  as  in  (#),we  find  from  the  first  and  second  equations  the 
values  of  R,'  and  R2.  To  find  Rt"  we  need  values  of  the  arms 
a6,  £6,  and  cb'.  By  measurement  from  a  drawing  we  find  that 

"06  =  32.7, lA5  =  20.5,  and  dT=  8. 3  feet. 

Substituting  these  values  in  the  third  equation  and  solving  for 
R/'  we  find  that 

3.100  X  32.7  +  6,200  X  20.5  -f  3,100  X  8.3 
Kj"  -  — 27j —  =  6,355  pounds. 

(c)     Using  the  third  set  of  conditions  of  equilibrium  stated 
in  Art.  35  we  obtain  the  following  three  equilibrium  equations  : 
As  in  (£),  taking  moments  about  the  right  and  left  ends  we  get 

Rj"X  40-3,100  X  32.7-6,200  X  20. 5- 3,100  X  8.3  =  0, 
and         -  R3  X  40  +  6,200  X  12.2  +  3,100  X  24.4  =  0. 

Choosing  the  peak  of  the  truss  as  the  origin  of  moments  for  the 
third  equation  we  find  that 

R/  X  14  +  R,"  X  20-  3,100  X  24.4-6,200  X  12.2  -  R.,  X  20  =  0. 

As  in  ( J)  we  find  from  the  first  two  equations  the  values  of  Rj"  and 
Rg.  These  values  substituted  in  the  third  equation  change  it  to 

R,'  X  14  -|-  6,373  X  20  -  3,100  X  24.4  -  6,200  X  12.2  -  3,782  X 
20  =  0 


102 


STATICS 


61 


P  ,  _  -6,373  X  20  +  3,100  X  24.4  +  6,200  x  12.2  -f-  3,782  x  20 
1  "  14 

=  7,104.* 

(d]  "When  using  the  fourth  sdt  of  conditions  we  always 
determine  the  reaction  at  the  roller  end  from  the  moment  equa- 
tion. Then,  knowing  'the  value  of  this  reaction,  draw  the  force 
polygon  for  all  the  loads  and  reactions  and  thus  determine  the 
magnitude  and  direction  of  the  other  reaction. 

Taking  moments  about  the  left  end,  we  find  as  in(#),(J),and 


Fig.  37. 


(c)  that  K2  =  3,782.  Then  draw  AB,  BC  and  CD  (Fig.  36)  to 
represent  the  wind  loads,  and  DE  to  represent  Rg.  Since  the  force 
polygon  for  all  the  forces  must  close,  EA  represents  the  magni- 
tude and  direction  of  the  left  reaction ;  it  scales  9,550  pounds. 

2.  It  is  required  to  determine  the  reactions  on  the  truss  of 
the  preceding  illustration  when  the  wind  blows  from  the  right. 

The  methods  employed  in  the  preceding  illustration  might  be 
used  here,  but  we  explain  another  which  is  very  simple.  The 
truss  and  its  loads  are  represented  in  Fig.  37.  Evidently  the 
resultant  of  the  three  wind  loads  equals  12,400  pounds  and  acts  in 
the  same  line  with  the  6,200-pound  load.  If  we  imagine  this 
resultant  to  replace  the  three  loads  we  may  regard  the  truss  acted 
upon  by  three  forces,  the  12,400-pound  force  and  the  reactions, 
and  these  three  forces  as  in  equilibrium.  Now  when  three  forces 


*  The  slight  differences  in  the  answers  obtained  from  the  different  sets 
of  equilibrium  equations  are  due  to  inaccuracies  in  the  measured  arms  of 
some  of  the  forces. 


103 


62  STATICS 

are  in  equilibrium  they  must  be  concurrent  or  parallel,  and  since 
the  resultant  load  (12,400  pounds)  and  Ik  intersect  at  O,  the  line 
of  action  of  1^  must  also  pass  through  O.  Hence  the  left 
reaction  acts  through  the  left  support  and  O  as  shown.  "We  are 
now  ready  to  determine  the  values  of  Rj  and  R^  Lay  off  AB  to 
represent  the  resultant  load,  then  from  A  and  B  draw  lines 
parallel  to  Ej  and  R^,  and  mark  their  intersection  C.  Then  BC 
and  CA  represent  the  magnitude  and  directions  of  R2  and  Rt 
respectively;  they  scale  6,380  and  8,050  pounds. 


PH 


. 


Fig.  38. 
EXAMPLE  FOR  PRACTICE. 

1.     Determine  the  reactions  on  the  truss  represented  in  Fig.  26 

due  to  wind  pressure,  the  distance  between  trusses  being  15  feet, 

supposing  that  both  ends  of  the  truss  are  fastened  to  the  supports. 

.          j  Reaction  at  windward  end  is  6,682^  pounds. 

(  Reaction  at  leewird  end      is  3,037|  pounds. 

VII.     ANALYSIS    OF  TRUSSES    (CONTINUED)  ;    METHOD  OF 
SECTIONS. 

38.  Forces  in  Tension  and  Compression  flembers.     As  ex. 
plained  in  "  Strength  of  Materials  "  if  a  member  is  subjected  to 
forces,  any  two  adjacent  parts  of  it  exert  forces  upon  each  other 
which  hold  the  parts  together.     Figs.  38  (a)  and  38  (7>)  show  how 
these  forc&a  act  in  a  tension  and  in  a  compression  member.     F'  is 
the  force  exerted  on  the  left  part  by  the  right,  and  F"  that  exerted 
on  the  right  part  by  the  left.     The  two  forces  F'  and  F"  are  equal, 
and  in  a  tension  member  are  pulls  while  in  a  compression  member 
they  are  pushes. 

39.  Method  of  Sections.     To  determine  the  stress  in  a  mem- 
ber  of  a  truss  by  the   method  explained   in  the  foregoing    (the 
"  method  of  joints  "),  we  begin  at  one  end  of  the  truss  and  draw 
polygons  for  joints  from  that  end  until  we  reach  one  of  the  joints 


104 


STATICS 


63 


to  which  that  member  is  connected.  If  the  member  is  near  the 
middle  of  a  long  truss,  such  a  method  of  determining  the  stress 
in  it  requires  the  construction  of  several  polygons.  It  is  some- 
times desirable  to  determine  the  stress  in  a  member  as  directly  as 
possible  without  having  first  determined  stresses  in  other  members. 
A  method  for  doing  this  will  now  be  explained  ;  it  is  called  the 
method  of  sections. 

Fig.  39  (a)  is  a  partial  copy  of  Fig.  16.  The  line  LL  is  in- 
tended  to  indicate  a  "  section  "  of  the  truss  "  cutting "  members 
24,131  and  36\  Fig.  39  (b)  and  (<?)  represents  the  parts  of  the  truss 
to  the  left  and  right  of  the  section.  By  "  part  of  a  truss "  we 
mean  either  of  the  two  portions  into  which  a  section  separates  it 
when  it  cuts  it  completely. 


Fig.  39. 

Since  each  part  of  the  truss  is  at  rest,  all  the  forces  acting  on 
each  part  are  balanced,  or  in  equilibrium.  The  forces  acting  on 
each  part  consist  of  the  loads  and  reactions  applied  to  that  part  to- 
gether with  the  forces  exerted  upon  it  by  the  other  part.  Thus  the 
forces  which  hold  the  part  in  Fig.  39  (&)  at  rest  are  the  1,500- 
and  3,000-pound  loads,  the  reaction  6,000  and  the  forces  which 
the  right  part  of  the  cut  members  exert  upon  the  left  parts.  These 
latter  forces  are  marked  F/,  F2'  and  F3' ;  their  senses  are  unknown. 


105 


64 


STATICS 


but  each  acts  along  the  axis  of  the  corresponding  member.  The 
forces  which  hold  the  part  in  Fig.  39  (c)  at  rest  are  the  two  3,000- 
pound  loads,  the  1,500-pound  load,  the  right  reaction  6,000 
pounds  and  the  forces  which  the  left  parts  of  the  cut  members 
exert  upon  the  right  parts.  These  are  marked  F/,  F/  and  F3"; 
their  senses  are  also  unknown  but  each  acts  along  the  axis  of  the 
corresponding  member.  The  forces  F/  and  F/',  F2'  and  F2",  and 
F/  and  F/'  are  equal  and  opposite;  they  are  designated  differently 
only  for  convenience. 

If,  in  the  system  of  forces  acting  on  either  part  of  the  truss, 
there  are  not  more  than  three  unknown  forces,  then  those  three  can 
be  computed  by  "applying"  one  of  the  sets  of  the  conditions  of 
equilibrium  stated  in  Art.  35.*  In  writing  the  equations  of 
equilibrium  for  the  system  it  is  practially  necessary  to  assume  a 
sense  for  one  or  more  of  the  unknown  forces.  We  shall  always 

assume  that  such  forces  are 
putts  that  is,  act  away 
from  the  part  of  the  truss 
upon  which  they  are  exerted. 
Then  if  the  computed  value 
of  a  force  is  plus,  the  force 
is  really  a  pull  and  the 
member  is  in  tension  and  if 
the  value  is  minus,  then  the 
force  is  really  a  push  and  the 
member  is  in  compression. 

To  determine  the  stress  in  any  particular  member  of  a  truss 
in  accordance  with  the  foregoing,  "pass  a  section"  through  the 
truss  cutting  the  member  under  consideration,  and  then  apply  as 
many  conditions  of  equilibrium  to  all  the  forces  acting  on  either 
part  of  the  truss  as  may  be  necessary  to  determine  the  desired  force. 
In  passing  the  section,  care  should  be  taken  to  cut  as  few  members 
as  possible,  and  never  should  a  section  be  passed  so  as  to  cut  more 
than  three,  the  stresses  in  which  are  unknown;  neither  should  the 
three  be  such  that  they  intersect  in  a  point. 

*If,  however,  the  lines  of  action  of  the  three  forces  intersect  in  a  point  then 
the,  statement  is  not  true. 


(5) 


Fig.  40. 


106 


STATICS  65 

Examples.  1.  It  is  required  to  determine  the  amount  and 
kind  of  stress  in  the  member  24  of  the  truss  represented  in  Fig. 
39  (a)  when  loaded  as  shown. 

Having  determined  the  reactions  (6,000  pounds  each)  we  pass 
a  section  through  the  entire  truss  and  cutting  24;  LL  is  such  a 
section.  Considering  the  part  of  the  truss  to  the  left  of  the 
section,  the  forces  acting  upon  that  part  are  the  two  loads,  the  left 
reaction  and  the  forces  on  the  cut  ends  of  members  24,. 34  and  36 
(F/,  F2',  and  F3').  F/  can  be  determined  most  simply  by  writing 
a  moment  equation  using  (3)  as  the  origin,  for  with  respect  to 
that  origin  the  moments  of  F2'  and  F3'  are  zero,  and  hence  those 
forces  will  not  appear  in  the  equation.  Measuring  from  a  large 
scale  drawing,  we  find  that  the  arm  of  F/  is  7  feet  and  that  of 
the  3,000-pound  load  is  3.5  feet.  Hence 

(F/  X  7)  +  (6,000  X  14)-(1,500  X  14)-- (3,000  X  3.5)=  0 

-  (6,000  X  14)  +  (1,500  X  14)  +  (3,000  X  3.5)          _  _m 
or  r  x  = ~  i  ,ouu 

The  minus  sign  means  that  F/  is  a  push  and  not  a  pull,  hence  the 
member  24~is  under  7,500  pounds  compression. 

The  stress  in  the  member  24  may  be  computed  from  the 
part  of  the  truss  to  the  right  of  the  section.  Fig.  39  (c)  repre- 
sents that  part  and  all  the  forces  applied  to  it.  To  determine 
F/'  we  take  moments  about  the  intersection  of  F2"  and  F3". 
Measuring  from  a  drawing  we  find  that  the  arm  of  F/'  is  7  feet, 

that  of  the  load  at  joint  (4)  is  7  feet, 

that  of  the  load  at  joint  (5)  is  17 . 5  feet, 

that  of  the  load  at  joint  (7)  is  28  feet, 

and  that  of  the  reaction  is  28  feet. 
Hence,  assuming  F/'  to  be  a  pull, 
— (F/'  X  7) +  (3,000  X  7) +  (3,000  X  17. 5) +  (1,500  X  28)— (6,000 

X  28)  =  0, 

„  „  _  (3,000  X  7) +  (3,000  X  17. 5) +  (1,500  X  28)  -(6,000  X28) 
or  *i    -  7 

=  —  7,500 

The  minus  sign  means  that  F,"  is  a  push,  hence  the  member 
2T  is  under  compression  of  7,500  pounds,  a  result  agreeing  with 
that  previously  found. 


107 


66 


STATICS 


2.     It  is  required  to  find  the  stress  in  the  member  gh  of  the 
truss  represented  in  Fig.  25,  due  to  the  loads  shown. 

If  we  pass  a  section  cutting  &/,  gh  and  he,  and  consider  the 
left  part,  we  get  Fig.  40,  the  forces  on  that  part  being  the  2,000- 
pound  load,  the  left  reaction,  and  the  forces  Flf  F2  and  F3  exerted 
by  the  right  part  on  the  left.  To  compute  F2  it  is  simplest  to 
use  the  condition  that  the  algebraic  sum 
of  all  the  vertical  components  equals  zero. 
Thus,  assuming  that  F2  is  a  pull,  and 
since  its  angle  with  the  vertical  is  30°, 

F2  cos  30°  -2,000  -f  3,000  =  0;  or, 

2,000-3,000      -1,000 

"0866-  =    -1'104' 


cos  30° 

The  minus  sign  means  that  F2  is  a  push, 
hence  the  member  is  under  a  compression 
of  1,154  pounds. 
3.     It  is  required  to  determine  the  stress  in  the  member  by 
of  the  truss  represented  in  Fig.  25,  due  to  the  loads  shown. 

If  we  pass  a  section  cutting  l)g  as  in  the  preceding  illustra- 
tion, and  consider  the  left  part,  we  get    Fig.    40.     To  compute 
Fj  it  is  simplest  to  write  the  moment  equa- 
tion for  all  the  forces  using  joint  5  as 
origin.     From  a  large  scale  drawing,  we 
measure  the  arm  of  ¥1  to  be  13.86  feet 
hence,  assuming  Fj  to  be  a  pull, 

Fj  X  13.86  -  2,000  X  8  +  3,000  X  16  =  0 ; 


_ 


2,000  X  8  -  3,000  X  16      -  32,000 


13.86 


13.86 
-2,310. 


[4ooolbs. 

Fig.  42. 


The  minus  sign  means  that  Fx  is  a  push;  hence  the  member  is 
under  a  compression  of  2,308  pounds. 

The  section  might  have  been  passed  so  as  to  cut  members  lg, 
fg,  and/0,  giving  Fig.  41  as  the  left  part,  and  the  desired  force 
might  be  obtained  from  the  system  of  forces  acting  on  that  part 
(3,000,  2,000,  F15  F2,  and  F3.)  To  compute  Fj  we  take  momente 
about  the  intersection  of  F2  and  F3,  thus 


108 


STATICS 


67 


Fj  X  13.86-2,000  X  8  -f  3,000  X  16  =  0. 

This  is  the  same  equation  as  was  obtained  in  the  first  solution, 
and  hence  leads  to  the  same  result. 

4.  It  is  required  to  determine  the  stress  in  the  member  T2 
of  the  truss  represented  in  Fig.  26,  due  to  the  loads  shown. 

Passing  a  section  cutting  members  12  and  14,  and  consider, 
ing  the  left  part,  we  get  Fig.  42.  To  determine  Fj  we  may  write 
a  moment  equation  preferably  with  origin  at  joint  4,  thus: 

Fj  X  4.47 +  4,000  X  10  =  0*; 
or,  F!  =  —     ^7-= — '•—  =  -  8,948  pounds, 

the  minus  sign  meaning  that  the  stress  is  compressive. 

Fj  might  be  determined  also  by  writing  the  algebraic  sum  of 


Fig.  43. 

the  vertical  components  of  all  the  forces  on  the  left  part  equal  to 
zero,  thus: 

Ft  sin  26°  34'  +  4,000  =  0; 
-4,000          -4,000 


agreeing  with  the  first  result. 

EXAMPLES  FOR  PRACTICE. 

1.  Determine  by  the  method  of  sections  the  stresses  in  mem- 
bers  23,  25,  and  45  of  the  truss  represented  in  Fig.  26,  due  to  the 
loads  shown. 

(  Stress  in  M  =  -  5,600  pounds, 

Ans.  -|  Stress  in  25"=  -  3,350  pounds. 

(  Stress  in  45  =  +  8,000  pounds 

*  The  arm  of  FI  with  respect  to  (4)  is  4.47  feet. 


109 


68 


STATICS 


2.     Determine  the  stresses  in  the  members  12, 15,  34,  and  56 
of  the  truss  represented  in  Fig.  27,  due  to  the  loads  shown. 

j  Stress  in  12  =  -  11,170  pounds, 
J  Stress  in  T5  =  +  10,000  pounds, 
1  Stress  in  "34  =  -  8,940  pounds, 
[Stress  in "56  =  +  6,000  pounds. 


1 

70oo 


(C) 

Fig.  44. 


76oolbal 

40.  Complete  Analysis 
of  a  Fink  Truss.  As  a  final 
illustration  of  analysis,  we 
shall  determine  the  stresses 
in  the  members  of  the  truss 
represented  in  Fig.  43,  due  to 
permanent,  snow,  and  wind 
loads.  This  is  a  very  com- 
mon type  of  truss,  and  is 
usually  called  a  "  Fink  "  or 
"French"  truss.  The  trusses 
are  assumed  to  be  15  feet 
apart;  and  the  roof  covering, 
including  purlins,  such  that  it 
weighs  12  pounds  per  square 
foot. 

The  length  from  one  end 
to  the  peak  of  the  truss  equals 


1/15*  -j-  302  =  1/1,125  =  33.54  feet, 
hence  the  area  of  the  roofing  sustained  by  one  truss  equals 

(33.54  X  15)  2  =  1,006.2  square  feet, 
and  the  weight  of  that  portion  of  the  roof  equals 
1.006.2  X  12  =  12,074  pounds. 


no 


STATICS  60 

The  probable  weight  of  the  truss  (steel),  according  to  the  formula 
of  Art.  19,  is 

60 
15  X  60  (_+  1)=  3,060  pounds. 

The  total  permanent  load,  therefore,  equals 

12,074  +  3,060  =  15,134  pounds; 

the  end  loads  equal  ^  of  the  total,  or  950  pounds,  and  the  other 
apex  loads  equal  ^  of  the  total,  or  1,900  pounds. 

Dead  Load  Stress.  To  determine  the  dead  load  stresses, 
construct  a  stress  diagram.  Evidently  each  reaction  equals  one-half 
the  total  load,  that  is  7,600  pounds;  therefore  ABCDEFGHIJKA 
(Fig.  44 b)  is  a  polygon  for  all  the  loads  and  reactions.  First,  we 
draw  the  polygon  for  joint  1;  it  is  KABLK,  BL  and  LK  repre- 
senting; the  stress  in  bl  and  Ik  (see  record  Page  72  for  values). 

o  v  o  / 

Next  draw  the  polygon  for  joint  2;  it  is  LBCML,  CM  and  ML 
representing  the  stresses  in  cm  and  ml.  Next  draw  the  polygon 
for  joint  3;  it  is  KLMNK,  MN  and  NK  representing  the  stresses 
in  mn  and  nk. 

At  each  of  the  next  joints  (4 and  5),  there  are  three  unknown 
forces,  and  the  polygon  for  neither  joint  can  be  drawn.  We  might 
draw  the  polygons  for  the  joints  on  the  right  side  corresponding 
to  1,  2,  and  3,  but  no  more  until  the  stress  in  one  of  certain  mem- 
bers is  first  determined  otherwise.  If,  for  instance,  we  determine 
by  other  methods  the  stress  in  rk*  then  we  may  construct  the  poly- 
gon for  joint  4;  then  for  5,  etc.,  without  further  difficulty. 

To  determine  the  stress  in  rk,  we  pass  a  section  cutting  rk, 
gr,  and  eq,  and  consider  the  left  part  (see  Fig.  44c).  The  arms 
of  the  loads  with  respect  to  joint  8  are  7.5,  15,  22. 5>  and  30  feet; 
and  hence,  assuming  Fj  to  be  a  pull, 

-Fi  x  15-1,900  X  7.5-1,900  X  15-1,900  X  22.5-950x30 
+  7,600  X  30  =  0;  or, 

-,_  -1,900X7.5-1,900X15-1,900X22.5-950X30+7,600X30 
Fl~  -15" 

=  7,600  pounds 

Since  the  sign  of  Fj  is  plus,  the  stress  in  rk  is  tensile. 


Ill 


70 


STATICS 


Now  lay  off  KR  to  represent  the  value  of  the  stress  in  ki 
just  found,  and  then  construct  the  polygon  for  joint  4.  The  poly- 
gon is  KNORK,  NO  and  OR  representing  the  stresses  in  no  and 
or.  Next  draw  the  polygon  for  joint  5;  it  is  ONMCBPO,  DP 
and  PO  representing  the  stresses  in  dp  and  po.  Next  draw  the 


polygon  for  joint  6  or  joint  7;  for  6  it  is  PDEQP,  EQ  and  QP 
representing  the  stresses  in  eq  and  qp.  At  joint  7  there  is  now 
but  one  unknown  force,  namely,  that  in  qr.  The  polygon  for  the 
three  others  at  that  joint  ia  ROPQ;  and  since  the  unknown  force 
iimst  close  the  polygon,  QR  must  represent  that  force,  and  must 
be  parallel  to  qr. 


112 


STATICS  71 

On  account  of  the  symmetry  of  loading,  the  stress  in  any 
member  on  the  right  side  is  just  like  that  in  the  corresponding 
member  on  the  left;  hence,  it  is  not  necessary  to  draw  the  diagram 
for  the  right  half  of  the  truss. 

Snow=Load  Stress.  The  area  of  horizontal  projection  of  the 
roof  which  is  supported  by  one  truss  is  60  X  15  =  900  square 
feet;  hence  the  snow  load  borne  by  one  truss  is  900  X  20  =  18,000 
pounds,  assuming  a  snow  load  of  20  pounds  per  horizontal 
square  foot.  This  load  is  nearly  1.2  times  the  dead  load,  and 
is  applied  similarly  to  the  latter;  hence  the  snow  load  stress  in 
any  member  equals  1.2  times  the  dead  load  stress  in  it.  We 
record,  therefore,  in  the  third  column  of  the  stress  record,  numbers 
equal  to  1.2  times  those  in  the  second  as  the  snow-load  stresses. 

Wind  Load  Stress.  The  tangent  of  the  angle  which  the 
roof  makes  with  the  horizontal  equals  -if  or  j;  hence  the  angle  is 
26°  34',  and  the  value  of  wind  pressure  for  the  roof  equals 
practically  29  pounds  per  square  foot,  according  to  Art.  19.  As  pre- 
viously explained,  the  area  of  the  roof  sustained  by  one  truss  equals 
1,006.2  square  feet;  and  since  but  one-half  of  this  receives  wind 
pressure  atone  time,  the  wind  pressure  borne  by  one  truss  equals 

503.1  X  29  =  14,589.9,  or  practically  14,600  pounds. 

When  the  wind  blows  from  the  left,  the  apex  loads  are  as 
represented  in  Fig.  45a,  and  the  resultant  wind  pressure  acts 
through  joint  5.  To  compute  the  reactions,  we  may  imagine  the 
separate  wind  pressures  replaced  by  their  resultant.  We  shall 
suppose  that  both  ends  of  the  truss  are  fixed;  then  the  reactions 
will  be  parallel  to  the  wind  pressure.  Let  Rj  and  R^  denote  the 
left  and  right  reactions  respectively;  then,  with  respect  to  the 
right  end,  the  arma  of  Rj  and  the  resultant  wind  pressure  (as  may 
be  scaled  from  a  drawing)  are  16.77  +  36.89  and  36.89  feet 
respectively;  and  with  respect  to  the  left  end,  the  arms  of  R2and 
the  resultant  wind  pressure  are  16.77  +  36.89  and  16.77  feet 
respectively. 
Taking  moments  about  the  right  en  1  we  find  that 

-  14,600  X  36.89  +  B,X  (16.77  +  36.89)  =  0; 

_       14,600  X  36.89 

B»=  16.77  +  36.89 


113 


72 


STATICS 


Taking  moments  about  the  left  end,  we  find  that 

14,600  X  16.77  -  K2X  (16.77  +  36.89)  =  0  ; 
14,600X16.77 


16.77  +  36. 


=:  4'565 


To  determine  the  stresses  in  the  members,  we  construct  a 
stress  diagram.  In  Fig.  45  &,  AB,  BC,  CD,  DE,  and  EF  represent 
the  wind  loads  at  the  successive  joints,  beginning  with  joint  1. 
The  point  F  is  also  marked  G,  H,  I,  and  J,  to  indicate  the  fact 
that  there  are  no  loads  at  joints  9,  10,  11,  and  12.  JK  represents 
the  right  reaction,  and  KA  the  left  reaction. 

We  may  draw  the  polygon  for  joint  1  or  12;  for  1  it  is 
KABLK,  BL  and  LK  representing  the  stresses  in  II  and  lie.  "We 
may  next  draw  the  polygon  for  joint  2;  it  is  LBCML,  CM  and 
ML  representing  the  stresses  in  cm,  and  ml  . 

Stress  Record. 


•KAHUKBMfe 

Dead  Load. 

Snow  Load. 

Wind  Left. 

Wind  Eight. 

Resultant. 

Resultant. 

bl 

-14,700 

-17,600 

-16,400 

15,000 

-  48,700 

-32,300 

cm 

-  13,700 

-16,400 

-15,900 

15,000 

-46,000 

-30,100 

dp 

-12,600 

-  15,100 

-15,400 

15,000 

-  43,100 

-28,000 

eq 

-11,600 

-13,900 

-14,900 

15,000 

-40,400 

-26,500 

Im 

-  1,650 

-  2,000 

-  3,700 

0 

-   7,350 

-   5,350 

mn 

+  1,650 

+  2,000 

+  3,700 

0 

+  7,350 

+  5,350 

no 

-  3,300 

-  4,000 

-   7,400 

0 

-14,700 

-  10,700 

op 

+  1,850 

+  2,200 

+  4,100 

0 

+  8,150 

+  5,950 

pq 

-  1,650 

-  2,000 

-  3,700 

0 

-   7,350 

-   5,350 

rq 

+  5,000 

+  6,000 

+11,000 

0 

+22,000 

+16.000 

ro 

+  3,400 

+  4,100 

+  7,400 

0 

+14,900 

+10,800 

kl 

+13,300 

+16,000 

+18,300 

+  6,100 

+47,600 

+31,600 

kn 

+11,300 

+13,600 

+14,200 

+  6,100 

+39,100 

+25,500 

kr 

+  8,000 

+  9,600 

+  6,100 

+  6,100 

+23,700 

+17,600 

kv 

+11,300 

+13,600 

+  6,100 

+14,200 

+39,100 

+25,500 

kx 

+13,300 

+16,000 

+  6,100 

+18,300 

+47,600 

+31,600 

ru 

+  3,400 

+  4,100 

0 

+  7,400 

+14,900 

+10,800 

rs 

+  5,000 

+  6,000 

0 

+11.000 

+22,000 

+16,000 

st 

-  1,650 

-  2,000 

0 

-3,700 

-   7,350 

-  5,350 

tu 

+  1,850 

+  2,200 

0 

+  4,100 

+  8,150 

+  5,950 

uv 

-  3,300 

-  4,000 

0 

-   7,400 

-  14,700 

-  10,700 

vw 

+  1,650 

+  2,000 

0 

-  3,700 

+  7,350 

+  5,350 

wx 

-  1,650 

-  2,000 

0 

-  3,700 

-  7,350 

-  5,350 

f* 

-11,600 

-13,900 

15,000 

-14,900 

-  40,400 

-26,500 

at 

-12,600 

-  15,100 

15,000 

-  15.400 

-  43,100 

-28,000 

hw 

-  13,700 

-16,400 

15,000 

-15,900 

-46,000 

-30,100 

ix 

-  14,700 

-17,600 

15,000 

-16,400 

-  48,700 

-32,300 

114 


STATICS  73 


We  may  draw  next  the  polygon  for  joint  3  ;  it  is  KLMNK, 
and  NK  representing  the  stresses  in  mn  and  tik.  No  polygon  for  a 
joint  on  the  left  side  can  now  be  drawn,  but  we  may  begin  at  the 
right  end.  For  joint  12  the  polygon  is  JKXIJ,  KX  and  XI 
representing  the  stresses  in  Tfx  and  xi. 

At  joint  11  there  are  three  forces  ;  and  since  they  are 
balanced,  and  two  act  along  the  same  line,  those  two  must  be  equal 
and  opposite,  and  the  third  must  equal  zero.  Hence  the  point  X 
is  also  marked  ~W  to  indicate  the  fact  that  XW,  or  the  stress  in 
xw,  is  zero.  Then,  too,  the  diagram  shows  that  WH  equals  XI. 
Having  just  shown  that  there  is  no  stress  in  xw,  there  are  but 
three  forces  at  joint  13.  Since  two  of  these  act  along  the  same 
line,  they  must  be  equal  and  opposite,  and  the  third  zero.  There- 
fore the  point  W  is  also  marked  V  to  indicate  the  fact  that  WV, 
or  the  stress  in  wv,  equals  zero.  The  diagram  shows  also  that  VK 
equals  XK.  This  same  argument  applied  to  joints  9,  15,  10,  and 
14  successively,  shows  that  the  stresses  in  st,  tu,  uv,  urt  and 
sr  respectively  equal  zero.  For  this  reason  the  point  X  is  also 
marked  UTS  and  R.  It  is  plain,  also,  that  the  stresses  in  sf  and 
tg  equal  those  in  wh  and  xi,  and  that  the  stress  in  kr  equals  that 
in  lev  or  lex.  Remembering  that  we  are  discussing  stress  due  to 
wind  pressure  only,  it  is  plain,  so  far  as  wind  pressure  goes,  that 
the  intermediate  members  on  the  right  side  are  superfluous. 

We  may  now  resume  the  construction  of  the  polygons  for  the 
joints  on  the  left  side.  At  joint  4,  we  know  the  forces  in  the 
members  len  and  &/•;  hence  there  are  only  two  unknown  forces 
there.  The  polygon  for  the  joint  is  KNORK,  NO  and  OR  repre- 
senting the  stresses  in  no  and  or.  The  polygon  for  joint  5  may 
be  drawn  next  ;  it  is  OKMCDPO,  DP  and  PO  representing  the 
stresses  in  dp  and  po.  The  polygon  for  joint  6  or  joint  7  may  be 
drawn  next  ;  for  6  it  is  PDEQP,  EQ  and  QP  representing  the 
stresses  in  eq  and  qp.  At  joint  7  there  is  but  one  unknown  force, 
and  it  must  close  the  polygon  for  the  known  forces  there.  That 
polygon  is  ROPQ  ;  hence  QR  represents  the  unknown  force.  (If 
the  work  has  been  correctly  and  accurately  done,  QR  will  be 
parallel  to  qr). 

When  the  wind  blows  upon  the  right  side,  the  values  of  the 
reactions,  and  the  stresses  in  any  two  corresponding  members,  are 


115 


74  STATICS 

reversed.  Thus,  when  the  wind  blows  upon  the  left  side,  the 
stresses  in  Td  and  fco  equal  18,300  and  6,100  pounds  respectively  ; 
and  when  it  blows  upon  the  right  they  are  respectively  6,100  and 
18,300  pounds.  It  is  not  necessary,  therefore,  to  construct  a  stress 
diagram  for  the  wind  pressure  on  the  right.  The  numbers  in  the 
fifth  column  (see  table,  Page  72)  relate  to  wind  right,  and  were 
obtained  from  those  in  the  fourth. 

4i.  Combination  of  Dead,  Snow,  and  Wind-Load  Stresses. 
After  having  found  the  stress  in  any  member  due  to  the  separate 
loads  (dead,  snow,  and  wind),  we  can  then  find  the  stress  in  that 
member  due  to  any  combination  of  loads,  by  adding  algebraically 
the  stresses  due  to  loads  separately.  Thus,  in  a  given  member, 
suppose: 

Dead-load  stress  =  -f  10,000  pounds, 

Snow-load      "  =+15,000 

Wind-load      "  (right)  =   -  12,000          " 
"          "   (left)      =  -f    4,000 

Since  the  dead  load  is  permanent  (and  hence  the  dead-load  stress 
also)  the  resultant  stress  in  the  member  when  there  is  a  snow  load 
and  no  wind  pressure,  is 

+  10,000  +  15,000  =  +  25,000  pounds  (tension)  ; 

when  there  is  wind  pressure  on  the  right,  the  resultant  stress 
equals 

+  10,000  -  12,000  =  -  2,000  pounds  (compression)  ; 

when  there  is  wind  pressure  on  the  left,  the  resultant  stress  is 
+  10,000  -f  4,000  =  +  14,000  pounds  (tension)  ; 

and  when  there  is  a  snow  load  and  wind  pressure  on  the  left,  the 
resultant  stress  is 

+  10,000  +  15,000  +  4,000  =  +  29,000  pounds  (tension). 

If  all  possible  combinations  of  stress  for  the  preceding  case  be 
made,  it  will  be  seen  that  the  greatest  tension  which  can  come 
upon  the  member  is  29,000  pounds,  and  the  greatest  compression 
is  23000  pounds. 

In  roof  trusses  it  is  not  often  that  the  wind  load  produces  a 
"  reversal  of  stress  "  (that  is,  changes  a  tension  to  compression,  or 


116 


STATICS  75 

vice  versa}\  but  in  bridge  trusses  the  rolling  loads  often  produce 
reversals  in  some  of  the  members.  In  a  record  of  stresses  the 
reversals  of  stress  should  always  be  noted,  and  also  the  value  of 
the  greatest  tension  and  compression  for  each  one. 

The  numbers  in  the  sixth  column  of  the  record  (Page  72)  are 

\          O  * 

the  values  of  the  greatest  resultant  stress  for  each  member.  It  is 
sometimes  assumed  that  the  greatest  snow  and  wind  loads  will  not 
come  upon  the  truss  at  the  same  time.  On  this  assumption  the 
resultant  stresses  are  those  given  in  the  seventh  column. 

EXAMPLE  FOR  PRACTICE. 

1.  Compile  a  complete  record  for  the  stresses  in  the  truss  of 
Fig.  24,  for  dead,  snow,  and  wind  loads.  See  Example  1,  Article 
27,  for  values  of  dead-load  stresses,  and  Example  2,  Article  29, 
for  values  of  the  wind-load  stresses.  Assume  the  snow  load  to 
equal  1.2  times  the  dead  load. 

After  the  record  is  made,  compute  the  greatest  possible  stress 
in  each  member,  assuming  that  the  wind  load  and  snow  load  will 
not  both  come  upon  the  truss  at  the  same  time. 

The  greatest  resultant  stresses  are  as  follows : 


Member. 
Result- 
ant.... 

«/     1     fe 
-14,95o'+17,800 

bg 

-10,400 

f9 

-8,875 

gh 

+7,820 

hi 

-8,875 

he 
-11,800 

ie 
+11,500 

id 
-13,850 

42.     Truss  Sustaining  a  Roof  of  Changing  Slope.     Fig  46 

represents  such  a  truss.     The  weight  of  the  truss  itself  can  be  esti- 
mated by  means  of  the  formula  of  Art.  19.     Thus  if  the  distance 
between  trusses  equals  12  feet,  the  weight  of  the  truss  equals 
qo 

W  =  12  X  32  (  25  +  1)  =  875  pounds. 

The  weight  of  the  roofing  equals  the  product  of  the  area  of 
the  roofing  and  the  weight  per  unit  area.  The  area  equals  12 
times  the  sum  of  the  lengths  of  the  members  12,  23",  84,  and  45, 
that  is,  12  X  36J  =  438  square  feet.  If  the  roofing  weighs  10 
pounds  per  square  foot,  then  the  weight  of  roofing  sustained  by 
one  truss  equals  438  X  10  =  4,380  pounds.  The  total  dead  load 
then  equals 

875  +  4,380  =  5,255  pounds; 


117 


76 


STATICS 


and  the  apex  dead  loads  for  joints  2,  3,  and  4  equal: 

—  X  5,255  =  1,314  (or  approximately  1,300) pounds; 
while  the  loads  for  joints  1  and  5  equal 

—  X  5,255  =  657  (or  approximately  650)  pounds. 

The  snow  loads  for  the  joints  are  found  by  computing  the 
snow  load  on  each  separate  slope  of  the  roof.     Thus,  if  the  snow 


Fig.  46. 

weighs  20  pounds  per  square  foot  (horizontal),  the  load  on  the  portion 
12  equals  20  times  the  area  of  the  horizontal  projection  of  the  por- 
tion of  the  roof  represented  by  127  This  horizontal  projection  equals 
8  X  12  (=  96)  square  feet;  snow  load  equals  96  X  20  (=  1,920) 
pounds.  This  load  is  to  be  equally  divided  between  joints  1  and  2. 

In  a  similar  way  the  snow  load  borne  by  23  equals  20  times 
the  area  of  the  horizontal  projection  of  the  roof  represented  by  23; 
this  horizontal  projection  equals  8  X  12  (  =  96)  square  feet  as 
before,  and  the  snow  load  hence  equals  1,920  pounds  also.  This 
load  is  to  be  equally  divided  between  joints  2  and  3. 

Evidently  the  loads  on  parts  34~and  4J5  also  equal  1,920 
pounda  each;  hence  the  apex  loads  at  joints  1  and  5  «qual  960 
pounds  and  at  joints  2,  3  and  4,  1,920  pounds. 


118 


STATICS  77 

The  wind  load  must  be  computed  for  each  slope  of  the  roof 
separately.  The  angles  which  12  and  23  make  with  the  horizontal, 
scale  practically  37  and  15  degrees.  According  to  the  table  of 
wind  pressures  (Art.  19),  the  pressures  for  these  slopes  equal 
about  35  and  20  pounds  per  square  foot  respectively.  Since  mem- 
ber 12  is  10  feet  long,  the  wind  pressure  on  the  37-degree  slope 
equals  10  X  12  X  35  =  4,200  pounds. 

This  force  acts  perpendicularly  to  the  member  12,  and  is  to 
be  equally  divided  between  joints  1  and  2  as  represented  in  the 
figure.  Since  the  member  23  is  8^  feet  long,  the  wind  pressure 
on  the  15 -degree  slope  equals 

8J  X  12  X  20  =  1,980  or  approximately  2,000  pounds. 

This  pressure  acts  perpendicularly  to  member  23,  and  is  to  be 
equally  divided  between  joints  2  and  3  as  represented. 

The  stress  diagram  for  dead,  snow,  or  wind  load  for  a  truss 
like  that  represented  in  Fig.  46,  is  constructed  like  those  previously 
explained ;  but  there  are  a  few  points  of  difference  in  the  analysis 
for  wind  stress,  and  these  will  be  explained  in  what  follows. 

.Example.  Let  it  be  required  to  determine  the  stresses  in  the 
truss  of  Fig.  46,  due  to  wind  loads  on  the  left  as  represented. 

It  is  necessary  to  ascertain  the  reactions  due  to  the  wind  loads; 
therefore,  find  the  resultant  of  the  wind  pressures,  see  Art.  37;  it 
equals  6,120  pounds  and  acts  as  shown.  Now,  if  both  ends  of  the  truss 
are  fastened  to  the  supports,  then  Jhe  reactions  are  parallel  to  the 
resultant  wind  pressure,  and  their  values  can  be  readily  found  from 
moment  equations.  Let  'Rl  and  R2  denote  the  left  and  right  reac- 
tions respectively;  then,  since  the  arms  of  R,  and  the  resultant 
wind  pressure  with  respect  to  the  right  end  equal  27.8  and  19.9 
feet  respectively, 

R,X  27.8  =  6,120  X  19.9  =  121,788  ; 

1 21  788 
hence,      Rz  =         *  ~  •  =  4,380  pounds  approximately. 

Since  the  arms  of  R2  and  the  "esultant  wind  pressure  with  respect 
to  the  left  support  are  27.8  and  7.9  feet  respectively, 

27.8  =  6,120  X  7.9  =  48,348  ; 


119 


78 


STATICS 


hence, 


=  1,740  pounds  approximately. 


The  next  step  is  to  draw  the  polygon  for  the  loads  and  reactions  ; 
so  we  draw  lines  AB,  BC,  CD,  and  DE  to  represent  the  loads  at 
joint  1,  the  two  at  joint  2,  and  that  at  joint  3,  respectively  ;  and 
then  EF  to  represent  the  right  reaction.  (If  the  reactions  have 
been  correctly  determined  and  the  drawing  accurately  done,  then 
FA  will  represent  the  left  reaction.) 

The  truss  diagram  should  now  be  lettered  (agreeing  with  the 
letters  on  the  polygon  just  drawn),  and  then  the  construction  of 
the  stress  diagram  may  be  begun.  Since  this  construction  presents 
no  points  not  already  explained,  it  will  not  be  here  carried  out. 

EXAMPLE  FOR  PRACTICE. 

Analyze  the  truss  of  Fig.  46  for  dead,  snow,  and  wind  loads 
as  computed  in  the  foregoing,  and  compute  the  greatest  resultant 
stress  in  each  member  due  to  combined  loads,  assuming  that  the 
snow  and  wind  do  not  act  at  the  same  time. 

| 
Stress  Record. 


Mem- 
ber. 

Dead. 

Snow. 

Wind  Left. 

Wind  Right. 

K.3  suit  ant. 

12 

-3,250 

-4,800 

-3,450 

-2,500 

-8,050 

23 

-2,700 

-4.00U 

-2,850 

-3,100 

-6,700 

16 

4-2,600 

+3,850 

+3,750 

+1,150 

+6,450 

26 

0 

0 

-2,000 

+1,250 

(    -2,000 
I  +1,250 

36 

0 

0 

+   450 

+   450 

+   450 

46 

0 

0 

+1,250 

-2,000 

(  +1,250 
\    -2000 

56 

+2,600 

+3,850 

+1,150 

+3,750 

+6,450 

43 

-2,700 

-4,000 

-3,100 

-2,850 

-6,700 

54 

-3,250 

-4,800 

-2,500 

-3,450 

-8,050 

120 


ROOF  TRUSSES 


1.  Classes  of  Roof  Trusses.  Roof  trusses  may  be  divided  into 
three  classes  according  to  the  shape  of  their  upper  chord.  These 
three  classes  are: 

(1)  Triangular  roof  trusses; 

(2)  Crescent  roof  trusses; 

(3)  Roof  trusses  other  than  these. 

Fig.  1  shows  various  forms  of  triangular  roof  trusses.  The 
Pratt  and  Howe  trusses  are  shown  respectively  by  a  and  b.  These 
trusses  obtain  their  name  on  account  of  their  web  bracing  being  of  the 
Pratt  or  Howe  type.  The  triangular  truss  in  most  common  use  is  the 
Fink,  next  to  which  is  the  Saw-tooth.  The  Fink  truss  is  built  in  a 
variety  of  forms,  as  shown  in  Fig.  1  (c,d,e, and/),  c  being  for  spans 
up  to  60  feet;  e  for  spans  up  to  70  feet,  and  d  and  /  for  spans  up  to  80 
feet  and  over.  The  great  advantage  of  this  style  of  truss  is  that 
many  of  its  members  have  the  same  stress,  and  therefore  it  can  be 
constructed  more  cheaply  on  account  of  the  fact  that  a  large  amount 
of  the  same  sized  material  can  be  purchased  a*t  once. 

When  the  top  chord  of  a  roof  truss  becomes  bent  as  shown  in 
Fig.  2,  the  truss  is  called  a  crescent  roof  truss.  The  bracing  in  the 
crescent  roof  trusses  is  not  of  any  particular  form,  being  as  a  usual 
thing  built  of  members  which  can  take  either  tension  or  compression. 
This  is  made  necessary  by  the  fact  that  the  curved  upper  chord  may 
cause  either  tension  or  compression  in  the  webbing,  according  to  the 
angle  of  its  inclination  with  the  horizontal. 

Roof  trusses  which  do  not  come  under  either  of  the  above  classes 
may  be  regarded  in  a  class  of  their  own.  To  this  class  belong  those 
trusses  which  are  somewhat  like  a  bridge  truss  in  that  the  two  chords 
are  horizontal  or  nearly  so.  The  ends  of  these  trusses  may  be  rec- 
tangular or  not.  For  various  types  of  this  class  of  truss,  see  Fig.  3. 

In  addition  to  the  above  classification,  which  is  based  on  the 
form  of  the  chords,  roof  trusses  may  be  divided  according  to  the 
manner  in  which  their  members  are  connected.  This  classification 


123 


ROOF  TRUSSES 


d.  Common  Fink  ( long  span)  e.  Modified  Fink  or  Fan>  Truss 


f  Modified  Fink  orFan{loncj  span) 


g.Saw  Tooth  h  Ketchum's  Modified  5aw  Tooth 

Fig.  1.    Triangular  Roof  Trusses. 


Fig.  2.    Crescent  Roof  Trusses. 


Fig.  3.    Trusses  with  Chords  Almost  Parallel. 


124 


nir 


ROOF  TRUSSES  3 

is  that  of  pin-connected  and  riveted.     For  a  definition  of  this,  and  for 
figures  showing  such  joints,  see  "Statics,"  pp.  22  and  23. 

Trusses  are  seldom  built  as  pin-connected  unless  they  are  of 
long  span,  since  roof  trusses  are  comparatively  light,  and  pin-con- 
nected trusses,  unless  of  considerable  weight,  do  not  give  very  great 
stiffness. 

Riveted  roof  trusses  are  used  for  nearly 
all  practical  purposes,  since  they  give  great 
rigidity  under  the  action  of  wind  and  of  mov- 
ing loads,  such  as  cranes,  which  may  be  at- 
tached to  them. 

2.  Physical  Analysis  of  Roof  Trusses. 
In  pin-connected  roof  trusses,  the  tension  mem-  Fjj±' 
bers  consist  of  I-bars  or  rods;  and  the  com- 
pression members  are  made  of  channels  or  angles  and  plates,  either 
plain  or  latticed.  In  riveted  trusses,  both  tension  and  compression 
members  are  made  up  of  angles  and  plates  or  a  combination  of  the  two. 
The  top  chords  of  roof  trusses  of  medium  span  usually  consist  of  two 
angles  placed  back  to  back.  If  the  stress  becomes  too  great  to  be 
taken  up  by  two  angles  larger  than  5  by  3£  inches,  then  two  angles  and 
a  plate  are  used  (see  Fig.  4).  In  case  the  roof  truss  is  of  great  size  and 


L 


Fig.  5.  Fig.  6 

Chord  Sections  for  Trusses  of  Long  Span. 


the  stresses  are  exceedingly  large,  the  chord  member  may  be  built  up 
in  a  manner  somewhat  similar  to  a  bridge  truss,  being  constructed  of 
two  channels  and  a  plate,  or  four  angles  and  three  plates.  Figs.  5  and 
6  show  cross-sections  of  chords  for  long-span  riveted  trusses.  These 
cross-sections  may  also  be  used  for  pin-connected  trusses. 

The  web  members  of  a  truss  usually  consist  of  one  angle;  and 
if  this  is  insufficient,  two  angles  back  to  back  are  used.  Fig.  80, 
page  65,  gives  a  diagram  of  a  roof,  and  shows  not  only  the  roof  trusses 


125 


ROOF  TRUSSES 


but  also  various  other  parts  which  will  be  referred  to  in  the  succeeding 
articles. 

3.  Wind  Pressure  and  Snow  Loads.  The  wind  pressure  on  a 
flat  surface  varies,  of  course,  with  the  velocity  of  the  wind,  and  is  very 
closely  given  by  the  formula: 

P  =  0.004F2 

By  substituting  in  this  formula,  the  values  shown  in  Table  I  are  deter- 
mined for  given  velocities  in  miles  per  hour. 

TABLE  I 
Wind  Pressure  at  Various  Velocities 


VELOCITY 
(Miles  per  hour) 

PRESSURE 
(Lbs.  per  square  foot) 

REMARKS 

10 

0.4 

Breeze 

20 

1.6 

Strong  breeze 

30 

3.6 

Strong  wind 

40 

6.4 

High  wind 

50 

10.0 

Storm 

60 

14.4 

Heavy  storm 

70 

19.6 

Hurricane 

80 

25.6 

" 

100 

40.0 

" 

The  pressures  indicated  in  Table  I  are  perpendicular  to  the  direction 
of  the  wind.  When  the  wind  blows  on  an  inclined  surface,  the  wind 
is  assumed  to  be  acting  horizontally,  and  the  normal  component  on 

the  inclined  surface  is  deter- 
mined. This  component  is  not 
equal  to  the  horizontal  pressure 
times  the  sine  of  the  angle  of 
inclination,  as  one  would  sup- 
pose (see  Fig.  7),  but  is  greater 
by  a  small'  amount.  Roofs  are 
usually  figured  on  a  basis  of  40 
pounds  pressure  on  a  vertical 
surface.  The  value  of  the  nor- 
mal component  for  a  horizontal  wind  pressure  of  40  pounds  per 
square  foot,  is  given  on  page  24  of  "Statics,"  and  is  here,  for  con- 
venience, reduced  to  the  normal  pressure  for  any  given  pitch. 


Fig.  7.    Theoretical  Determination  of 
Normal  Component. 


126 


ROOF  TRUSSES  5 

PITCH  NORMAL  WIND  PRESSURE 

J 34  pounds  per  square  foot. 

30° 32       "  " 

i 30       "  "         " 

1 26       "  "         " 

t 22        " 

If  the  normal  pressure  on  a  roof  making  any  other  angle  with  the  hori- 
zontal is  desired,  see  "Statics,"  p.  24. 

The  determination  of  these  values  is  based  for  the  most  part  on 
data  obtained  by  experiment.  In  the  computations  relative  to  the 
design  of  buildings,  the  wind  is  usually  assumed  to  exert  a  pressure 
on  the  walls  of  30  pounds  per  square  foot. 

The     snowfall 


varies  with  the  lo- 
cality.    The  heav- 
iest     snow     loads 
which  come  upon  a 
roof  are  not  always 
in    the    locality  of 
the  heaviest  snow- 
fall, since  a  compar- 
atively light  snow- 
fall may  occur,  and 
if   this  is  followed 
by  wind  and  sleet,    - 
the  result  will  be  a 
load  greatly  in  ex- 

/ 

For  Pacific  Coast 
and  Arid  Regions  use 
one-half  tabular  values- 

t&jS 

\ 

30  "5 

tr 

•j 
J 

^ 

$<, 

^ 

/^ 

^.^ 

^^ 

/ 

Ice  an< 

i  Sleet  for  all  51 

apes 

0 

35                         40                       45                          50 
Latitude  in  Degrees. 

Fig.  8.    Unit  Snow  Loads. 

cess  of  the  snowfall  itself.  The  snow  load  per  square  foot  of  roof 
surface  varies  with  the  pitch  of  the  roof,  and  will  be  greater  the 
smaller  the  pitch.  The  ice  and  sleet  will  be  comparatively  constant. 
Fig.  8*  gives  values  of  snow  and  sleet  loads  which  are  recommended 
for  use.  It  is  customary  to  figure  the  snow  load  by  taking  it  as  so 
much  per  square  foot  of  horizontal  projection. 

EXAMPLES    FOR    PRACTICE 

1.  Compute  the  wind  panel  [load  on  a  roof  whose  pitch  is  \, 
and  whose  panel  length  is  15  feet,  the  distance  between  trusses  being 
16  feet. 

2.  Compute  the  snow  panel  load  for  the  truss  of  Problem  1,  above. 

*Ketchum's  "Steel  Mill  Buildings,"  p.  11. 


127 


6  ROOF  TRUSSES 

,4.  Weights  of  Roof  Trusses.  The  weight  of  a  roof  truss  varies 
with  the  material  of  which  it  is  constructed,  the  span,  the  distance 
between  trusses,  the  pitch,  and  the  capacity  of  the  truss.  The  actual 
weight,  of  course,  cannot  be  determined  until  after  the  truss  is 
designed;  but  an  approximate  weight  may  be  obtained  from  any  of 
the  empirical  formulae  which  are  now  in  use.  Table  II  gives  the 
most  common  and  best  of  the  empirical  formulae,  together  with  the 
names  of  their  authors. 

TABLE  II 
Formulae  diving:  Weights  of  Roof  Trusses 

FORMULA  AUTHOR 


W 


W  = 


Pal 


2  a 


(*  +  ^ 


+  r' 


W  =  al  (0 . 06  I  +  0 . 6)  for  heavy  loads 
W  =  01(0.04:1  +  0.4)   "   light        " 


Mansfield  Merriman 

E.  R.  Maurer,  (p.  23,  "Statics") 

N.  C.  Ricker 

Milo  S.  Ketchum* 

C.  W.  Bryan 

C.  E.  Fowler 


In  the  above  formulae, 

W  =  Weight  of  steel  in  truss,  in  pounds; 

P  =  Capacity  of  truss  in  pounds  per  square  foot  of  horizontal  projec- 
tion of  roof; 

r  =  Rise  of  peak,  in  feet; 

a  =  Distance  center  to  center  of  trusses,  in  feet; 
I  =  Span  of  truss,  in  feet. 

ROOF  COVERINGS 

5.  The  roof  is  covered  with  some  material  which  will  protect 
the  interior  of  the  building  from  the  action  of  the  elements.  This 
covering  may  consist  of  any  one  or  more  of  the  materials  which, 
together  with  their  weights  per  square  foot,  are  indicated  in  Table  III. 
The  weights  here  given  for  materials  which  must  be  laid  upon  sheath- 
ing, do  not  include  the  weight  of  the  sheathing,  which  is  given  sepa- 
rately. A  short  description,  together  with  necessary  information  for 
use  in  estimates,  will  now  be  given. 

*  "Steel  Mill  Buildings,"  p.  5. 


128 


ROOF  TRUSSES 


TABLE   III 
Approximate  Weights  of  Roof  Coverings 


MATERIAL 

WEIOHT  PER  SQUARE   FOOT 

White  pine  sheathing  1  inch  thick 
Yellow  pine  sheathing  1  inch  thick 
Batten  sheathing,  4-in.  by  1-in. 

3  11 
4 
2* 

)S. 

Slate 

10 

Skylight  glass,  including  frame 

10 

Tin 

1 

Shingles 

3 

Corrugated  steel 

2 

Flat  tiles 

12  to  25 

Corrugated  tiles 

10 

Concrete  slabs 

35  to  50 

Felt,  asphalt  and  gravel 

10 

Felt  and  gravel 

10 

Patent  roofings 

$  to    1} 

Sheet  steel 

'     1* 

Non-condensing  base 

1 

Fig.  9.    Method  of  Laying  Slate. 


Sheathing.  Sheathing  is  generally  laid  directly  upon  the  purlins 
(see  Article  6);  and  upon  this  are  laid  the  shingles,  slate,  tin,  or  tile. 
Sheathing  is  usually  made  of  a  single  thickness  of  planks,  1  to  2$ 
inches  thick,  laid  close  together.  In  some  cases,  however,  when 
batten  sheathing  is  used,  it 
is  spaced  from  2  to  4  inches 
apart.  This  has  the  advan- 
tage of  being  cheap  and  at 
the  same  time  allowing  good 
circulation  of  air  beneath 
the  roof  covering,  and  con- 
sequently dampness  due  to 

any  cause  will  soon  dry  out.     Batten  sheathing  is  much  used  where 
the  roof  covering  consists  of  slate,  shingles,  or  tile. 

Slate.  Roofing  slate  is  generally  of  the  characteristic  slaty  color, 
but  may  be  obtained  in  nature  in  greens,  purple,  reds,  and  other 
colors.  It  is  made  in  thicknesses  of  from  i  to  J  inch,  in  widths  from 
6  to  24  inches,  and  in  lengths  from  12  to  44  inches.  The  12  by  18  by 
-^-in.  slate  is  probably  the  most  commonly  used.  Slate  should  be 
laid  as  shown  in  Fig.  9,  and  the  pitch  of  the  roof  should  not  be  less 
than  J.  If  the  pitch  of  the  roof  is  less  than  this,  the  lap  should  be 
made  greater  than  3  inches,  as  is  shown  in  Fig.  9.  The  lap  should 
be  increased  at  least  \  inch  for  every  ^  in  pitch;  and  the  minimum 


129 


8  ROOF  TRUSSES 

pitch  should  never  be  less  than  £,  since  it  is  practically  impossible  to 
prevent  roofs  with  a  smaller  pitch  than  this  from  leaking,  especially 
if  a  strong  wind  is  blowing. 

The  number  of  different  sizes  of  slate  required  to  lay  100  square 
feet  of  surface,  and  also  their  weight,  are  given  in  the  handbooks  of 
the  various  slate  companies.  With  a  3-inch  lap,  it  takes  160  of  the 
size  "and  thickness  mentioned  above  to  lay  100  square  feet,  and  the 
total  weight  of  this  square  is  650  pounds.  Slate  is  one  of  the  most 
durable  of  roofing  materials.  Its  first  cost  is  high,  being  from  5  to 
8  dollars  per  hundred  square  feet;  but  the  cost  of  maintenance  is 
almost  nothing,  since  it  is  affected  neither  by  the  elements  nor  by  the 
action  of  gases  or  acids.  In  case  the  roof  would  be  subjected  to  the 
action  of  gases  or  acids,  it  is  advisable  to  use  copper  slating  nails. 

Skylight  Glass.     Skylights  usually  consist  of  glass  about  &  to 

First  Staqe )         Finished 


(-  Sheathing  -/  Sheathing  ^ 

Fig.  10.    Tin  Laid  with  Flat  Seam.  Fig.  11.    Tin  Laid  with  Standing  Seam. 

f  inch  in  thickness,  supported  on  light  members  of  iron  or  galva- 
nized iron  which  act  as  a  framework.  The  actual  weight  of  glass  of 
different  kinds  can  be  accurately  obtained  from  manufacturers'  cata- 
logues, and  the  student  is  referred  to  these;  they  may  be  had  by 
addressing  the  manufacturers  (see  Figs.  73  and  74). 

Tin.  This  is  made  by  coating  thin,  flat  sheets  of  iron  or  steel, 
either  with  tin  alone  or  with  a  mixture  of  tin  and  lead.  In  the  first 
case  the  product  is  called  bright  tinplate,  and  in  the  second  case  terne 
plate.  Terne  plate  must  not  be  used  where  it  will  be  subjected  to  the 
action  of  acids  or  corrosive  gases,  since  the  lead  coating  is  rapidly 
destroyed,  and  then  of  course  the  iron  also. 

Tin  plates  come  in  various  sizes  and  thicknesses;  but  usually  112 
come  in  one  box.  The  most  commonly  used  is  a  sheet  20  by  28 
inches,  and  of  sheet  iron  of  No.  27  gauge,  which  weighs  10  ounces'  to 
the  square  foot.  This  is  marked  "IX."  If  the  box  were  marked 
"1C,"  it  would  indicate  that  the  sheets  were  of  No.  29  gauge  metal, 
which  weighs  8  ounces  to  the  square  foot.  The  value  of  the  roofing 


130 


ROOF  TRUSSES  9 

depends  to  a  great  extent  upon  the  amount  of  tin  used  in  the  coating. 
This  will  vary  from  8  to  50  pounds  for  a  box  of  the  20  by  28-inch 
sheets. 

A  tin  roof  is  formed  by  fixing  together  a  number  of  these  sheets. 
The  sheets  may  be  connected  as  shown  in  Fig.  10,  or  as  shown  in  Fig. 
11.  In  the  first  case,  they  are  said  to  be  laid  with  a  flat  seam,  and 
in  the  second  case  they  are  said  to  be  laid  with  a  standing  seam.  Tin 
roofs  rot  out  very  readily  unless  they  are  kept  painted.  If  a  new  coat 


Covers 


Cavers  24" 


30" wide  before  corrugating 


2  Corruqafion  Side  Lap 
Covers  Z5V  Covers 


li  Corrugation  Side  Lap 

Covers   26k"  Covers  Z6V 


I  Corruqation  5ide  Lap 

Fig.  12.    Lapping  of  Corrugated  Steel. 

is  given  them  every  couple  of  years,  they  will  last  from  twenty  to 
thirty  years. 

Tin  can  be  laid  on  roofs  whose  pitch  is  very  small,  say  ^.  The 
first  cost  is  about  as  much  as  that  of  slate,  but  the  cost  of  mainte- 
nance is  very  high. 

Shingles.  Shingle  roofs  are  very  seldom  used  on  buildings  for 
manufacturing  purposes,  for  the  reason  that  they  take  fire  quite 
readily,  leak  quite  easily,  and  require  renewal  quite  often.  Shingles 
are  from  18  to  24  inches  long,  and  usually  run  from  2  to  8  inches  in 


131 


10 


ROOF  TRUSSES 


width,  although  they  can  be  obtained  of  a  uniform  width  of  from  4 
to  6  inches.  They  are  laid  like  slate,  the  lap  being  made  4  inches  or 
more.  They  should  never  be  laid  on  roofs  whose  pitch  is  less  than  £. 
It  takes  about  from  800  to  1,000  shingles  to  lay  100  square  feet  of 
roof.  The  cost  is  about  $5.00  per  100  square  feet;  but  under  the  best 
conditions,  the  life  of  shingles  is  only  about  ten  years. 

Corrugated  Steel.  Corrugated  steel  is  made  from  flat  sheets  of 
standard  gauges,  and  may  be  either  galvanized  or  left  as  it  comes 
from  the  rolls.  The  corrugations  are  of  different  sizeu  and  widths; 
the  total  width  of  the  plates 
runs  from  24  to  28  inches, 
and  their  length  from  5  to 
10  feet,  varying  by  ^  foot. 
The  sheet  most  used  for 


Fig.  13.    Showing  How  Steel  Roofing  is 
Fastened  to  Purlins. 


roof  construction  has  2i-inch 
corrugations;  is  26  inches  wide 
after  corrugating;  and  will 
cover  a  width  of  24  inches 
with  one  lap  and  2H  inches 
with  two  laps.  This  roofing 
should  be  laid  with  a  pitch  of 

not  less  than  \,  and  should  have  from  6  to  8  inches  lap  at  the  ends. 

For  further  information  regarding  the  method  of  lapping  and  the 

width  covered,  see  Fig.  12. 

Corrugated  steel  is  fastened  either  directly  to  wooden  purlins 

by  means  of  nails,  or  directly  to  iron  purlins  either  by  means  of  a 

bolt  and  clip  or  by  a  clinch  nail  (see  Fig.  13). 

It  is  often  advisable  to  know  the  strength  of  corrugated  steel 

when  supported  at  certain  distances  apart  by  supports  perpendicular 

to  the  corrugations.     This  unsupported  length  determines  in  many 

cases  the  spacing  of  the  purlins.     The  load  in  pounds  per  square  foot 

which  can  be  carried  by  a  plate  of  span  /,  parallel  to  the  corrugation, 

is  given  by  the  formula : 

W 


330  Sdt 


132 


ROOF  TRUSSES 


11 


in  which, 

I  =  Unsupported  length  of  sheet,  in  inches; 
t  =  Thickness  of  sheet,  in  inches; 
S  =  Allowable  unit-stress; 
d  =  Depth  of  corrugation,  in  inches. 

Table  IV,  giving  data  relative  to  corrugated  sheets,  is  taken 
from  page  172  of  the  Pocket  Companion  of  the  Carnegie  Steel  Com- 
pany (edition  of  1902),  where  also  other  valuable  information  is  given. 

TABLE  IV 
Corrugated  Steel  Data 


WEIGHT  IN   LBS.  PER   100  SQ.  FT.  OP  ROOF  WHEN  LAID 

NO.   BY 

BIRMINGHAM 

THICKNESS 
(Inches) 

WITH  6-iN.  END  LAP  AND  ONE  CORRUGATION,  2i-in., 
SIDE  LAP,   AND   LENGTH  or: 

5ft. 

6ft. 

7ft. 

8ft. 

9ft. 

10  ft. 

16 

0.065  in. 

365 

358 

353 

350 

348 

346 

18 

0.049 

275 

270 

267 

264 

262 

261 

20 

0.035 

196 

192 

190 

188 

186 

185 

22 

0.028 

156 

154 

152 

150 

149 

148 

24 

0.022 

123 

121 

119 

118 

117 

117 

26 

0.018 

101 

99 

97 

97 

96 

95 

Tiles.  One  of  the  most  common  sizes  of  plain  roofing  tile  is 
10-^  inches  long  by  6|  inches  wide  and  f  inch  thick.  Tile  of  this  size 
weigh  about  2^  pounds  each. 
They  are  laid  with  a  lap  equal  to 
one-half  their  length.  They  may 
be  laid  directly  upon  plank 
sheathing  in  a  manner  similar  to 
shingles  or  slate,  or  they  may  be 
laid  directly  upon  purlins  (see 
Figs.  14,  15,  and  16).  In  the 
first  case  they  are  nailed  directly 
to  the  sheathing,  and  in  the  second  case  they  are  connected  with  the 
purlins  either  with  copper  wire  or  clinch  nails.  Flat  tiles  are  usually 
laid  in  cement ;  corrugated  tiles  are  made  so  as  to  interlock,  and  conse- 
quently in  most  cases  require  no  cement.  One  convenience  of  the 
tile  roof  is  that  the  skylights  may  be  formed  by  laying  glass  tile  in 
place  of  the  other. 

Tile  roofs  are  very  substantial;  but  are  very  costly,  in  regard  not 
only  to  the  tiles  themselves,  but  also   in  regard  to  the  additional 


Fig.  14.    Method  of  Laying  Flat  Tile  on 
Plank  Sheathing. 


133 


12  ROOF  TRUSSES 

weight  required  in  the  trusses  by  reason  of  the  great  weight  to  be 
supported.  Tile  weigh  from  700  to  1,000  pounds  per  100  square  feet 
of  roof  surface.  They  cost  from  $12.00  to  $40.00  per  100  square  feet 
on  the  roof. 

Concrete  Slabs.  These  are  usually  moulded  directly  in  place 
by  suspending  forms  from  the  roof  trusses.  They  may  or  may  not  be 
reinforced,  and  in  any  case  are  usually  not  over  4  inches  in  thickness. 
Their  weight  is  about  50  pounds  per  square  foot.  Their  cost  is  from 
$16.00  to  $30.00  per  hundred  square  feet  of  roof  surface.  They  are 
expensive,  not  only  on  their  own  account,  but  also  from  the  fact  that 
the  weight  of  the  roof  trusses  must  be  increased  in  order  to  carry  the 


Fig.  15.    Ludowici  Tile  on  Steel  Purlins.  Fig.  16.    Ludowici  Tile  on  Sheathing. 

weight  of  the  slabs.     Concrete  roofing  may  be  used  on  roofs  wThich  are 
practically  flat,  |  inch  to  1  foot  being  sufficient  pitch. 

Felt  and  Asphalt.  This  roofing  is  laid  upon  shingles,  and  consists 
of  one  thickness  of  dry  felt,  three  or  four  thicknesses  of  roofing  felt 
well  cemented  together  with  asphalt  cement,  and  laid  with  good  laps 
where  they  join,  and  a  coating  of  from  100  to  200  pounds  of  asphalt 
per  100  square  feet  of  roof  surface.  Upon  this  asphalt,  while  hot, 
gravel  screened  through  a  f-inch  mesh  is  spread  in  the  quantity  of 
about  y  of  a  cubic  yard  per  100  square  feet.  This  class  of  roofing 
should  never  be  laid  on  roofs  whose  pitch  is  greater  than  ^,  since, 
when  heated  by  the  rays  of  the  sun,  the  asphalt  will  run  and  destroy 
the  surface.  It  gives  good  satisfaction  on  roofs  whose  pitch  is  -^. 
This  class  of  roofing  can  be  bought  in  rolls,  and  in  this  case  the  gravel 
is  exceedingly  fine,  being  screened  through  a  |-inch  mesh. 


134 


ROOF  TRUSSES  13 

Felt  and  Gravel  Roofing.  This  roofing  is  similar  to  the  above; 
only,  in  this  case,  tar  instead  of  asphalt  is  used  for  the  cementing  con- 
stituent. This  roofing  does  well  on  roofs  of  flat  pitch,  and  should 
never  be  used  on  roofs  whose  pitch  exceeds  $.  It  can  also  be  bought 
in  rolls  ready  for  laying,  in  which  case  the  gravel  is  screened  through 
a  |-inch  mesh.  The  prepared  roofings  are  cheaper  than  those  laid  by 
hand;  but  they  do  not  give  good  service  unless  great  care  is  taken 
to  fasten  them  down  securely.  In  economy  of  first  cost  and  main- 
tenance, they  are  equal  to  or  better  than  tin. 

Sheet  Steel.  This  should  not  be  laid  on  a  pitch  less  than  \,  unless 
the  ends  are  cemented  together  where  they  lap.  It  comes  in  sheets  28 
inches  wide  and  from  4  to  12  feet  long,  or  it  may  be  purchased  in 
rolls  26  inches  wide  and  about  50  feet  long.  When  used  in  sheets,  it 
may  be  had  with  standing  crimped  edges,  in  which  case  it  is  laid  as 

Wood  Nailing  5trips-y^ 

Sheet  Steely  rfjj^.     5teel  Roofinq.     ^elt  or  Tar  Paper 

foaoOQ 

^Sheathing  WireNettingJ        ^-Asbestos 

Fig.  17.    Method  of  Laying  Sheet  Steel          Fig.  18.    Method  of  Laying  Roofing  on  an 
•with  Crimped  Edges.  Anti-Condensing  Base. 

shown  in  Fig.  17.  In  case  it  comes  in  rolls,  it  may  be  laid  in  the  same 
manner  as  tin,  with  either  standing  seams  or  horizontal  flat  ones  as 
shown  in  Figs.  10  and  11.  Like  corrugated  steel,  it  comes  in  different 
gauges,  No.  28  being  that  most  commonly  used.  It  can  be  laid 
cheaper  than  tin,  on  account  of  the  long  lengths  obtainable. 

Patent  roofings  of  many  kinds  are  on  the  market.  These  come 
in  rolls  usually  from  2  feet  to  3  feet  wide,  and  cover  about  200  square 
feet  of  roof  surface.  The  basis  of  most  of  these  covers  is  asbestos, 
felt,  magnesia,  or  rubber;  and  this  is  treated  with  either  asphalt,  tar, 
or  some  other  preparation,  and  in  some  cases  is  covered  with  fine 
gravel. 

Non=Condensing  Roofing.  In  cases  where  a  metal,  slate,  or  tile 
roof  is  used  without  sheathing,  moisture  is  liable  to  condense  upon  the 
under  side  and  drip  on  the  floor  beneath.  This  can  be  prevented  by 
laying  the  material  upon  an  anti-condensing  base  consisting  of  a  layer 
of  wire  netting  on  top  of  which  are  placed  one  or  more  sheets  of  asbes- 
tos paper  about  TV  inch  thick  (see  Fig.  18). 


135 


14 


ROOF  TRUSSES 


6.  Rafters  and  Purlins.  Roof  trusses  are  usually  connected 
by  beams  running  from  one  to  the  other.  These  beams  are  called 
purlins.  In  case  the  purlins  are  spaced  too  far  apart  to  lay  the  roof 
covering  directly  upon  them,  beams  are  placed  upon  the  purlins,  and 
on  these  beams  the  roof  covering  is  placed.  These  beams  are  called 

rafters.      Raft- 
ers are  usually 
made  of  wood, 
while      purlins 
are     made     of 
channels,     I- 
beams,  Z-bars, 
and,  if  the  truss- 
es   are   spaced 
sufficiently 
close   together, 
tees  or  angles.  Figs. 
19  and  20  show  how 
rafters  and  purlins 
are  placed.    Fig.  21 
illustrates    the  use 
of  purlins  made  of 
tees.  As  purlins  are 
more  rigid  about  an 
axis    perpendicular 
to  their  webs,  they 
are    liable    to    sag 
toward    the    eaves 
at  their  center.    In 


Fig.  19.    Roof  Construction  in  which  Rafters  Supporting  the 
Sheathing  are  Laid  on  the  Purlins  which  Connect  the  Trusses. 


Fig.  20.    Sheathing  Laid  Directly  on  Purlins. 


this  case,  sag  rods  are  used,  as  shown  in  Fig.  22. 
EXAMPLES    FOR    PRACTICE 

1.  Compute  the  roof  rafters  if  the  purlins  are  spaced  10  feet  apart, 
the  roof  covering  weighs  10  pounds,  the  sheathing  4  pounds,  and  the  snow 
load  per  square  foot  of  roof  surface  12  pounds. 

This  problem  may  be  solved,  either  by  assuming  the  size  of  the 
rafters  and  computing  their  spacing,  or  by  assuming  the  spacing  and 
computing  the  size  of  the  rafters.  The  latter  method  is  the  one  most 
commonly  used.  The  spacing  of  rafters  is  from  18  inches  to  4  feet. 


136 


ROOF  TRUSSES 


15 


The  common  spacing  is  2  feet.     The  weight  of  the  rafter  itself  is 
neglected  in  its  design. 

The  total  weight  per  square  foot  which  comes  on  the  rafter  is 
12  +  10  +  4  =  26  pounds.  Since  each  rafter  carries  a  portion  of 
the  roof  10  by  2  feet,  the  total 
weight  on  one  rafter  is  10  X  2  X 
26  =  520  pounds.  The  moment 
created  by  this  weight  is  (520  X 
10  X  12)  -T-  8  =  7800  pound- 
inches.  This  should  be  equated  to 

O     T 

— .  Allowing  1  000  pounds  to  the 

.      ,  ,1  .,  Fig.  21.    Use  of  Purlins  Made  of  Tees. 

square  inch  as  the  unit-stress  on 

the    extreme    fibre,    and    noting    that    I  -r-  C  = -;--=  — 

there  results: 


000  bd2 


=  7800 


d  =  N/46.8  H-  6 

The  market  widths  of  rafters  are  l£,  2,  3,  and  4  inches,  2  inches  being 
the  size  usually  employed.     Substituting  in  the  above  formula,  we 

have: 


Fig.  22.    Use  of  Sag  Rods  to  Prevent  Sagging 
of  Purlins  at  their  Center. 


d=  V46.8  H-  2  =  4.8  inches. 

The  rafters  will  be  made  2 
by  6  inches,  since  this  is  the 
nearest  market  size.  If  a 
3-foot  spacing  of  rafters  was 
used,  the  required  depth 
would  be  5.92  inches,  and  a  2  by  6-inch  would  still  be  used.  This 
spacing  and  this  size  of  rafter  would  be  the  one  to  employ  in  the 
solution  of  the  above  problem. 

2.  Design  the  purlin  for  the  roof  of  Problem  1,  above,  if  the  trusses 
are  spaced  16  feet  apart. 

The  rafters  are  spaced  so  close  together  that  their  own  weight, 
the  weight  of  the  roof  covering,  and  the  snow  load  may  be  considered 
as  uniformly  distributed  over  the  purlin.  The  total  weigh*  which 
comes  upon  one  purlin  is  the  weight  of  snow  and  roof  covering  on  -a 
space  16  feet  long  and  10  feet  wide.  This  weight  is: 


137 


16  ROOF  TRUSSES 

Snow  load  =  10  X  16  X  12  1  920  pounds 

Roof  covering  =  10  X  16  X  14  2  240       " 

16  rafters  6  by  2-in.,  10  feet  long,  at  3  Ibs.  per  144  cu.  in.       480        " 

Total         4  640  pounds 
The  moment  caused  by  this  weight  is: 

(4  640  X  16  X  12)  -5-  8  =  111  360  pound-inches. 
The  determination  of  the  beam  which  will  be  used  to  withstand 
this  bending  moment  is  made  by  means  of  its  section  modulus.    The 

formula  —  =  -  is  used  in  the  design  of  beams.     The  values  of  / 

»S        c 

and  c  are  constant  for  any  given  beam,  and  therefore  the  value  of 
/  -r-  c  for  any  particular  beam  is  a  constant,  and  this  constant  is  called 
the  section  modulus.  It  is  therefore  evident  that  if  we  have  a  certain 
bending  moment  and  a  certain  allowable  unit-stress,  we  can  obtain 
the  value  of  the  section  modulus  by  dividing  the  moment  by  the 
allowable  unit-stress.  Then,  looking  into  one  of  the  steel  handbooks, 
the  beam  can  be  determined  which  will  have  a  section  modulus  equal 
to  or  slightly  in  excess  of  the  value  that  has  been  obtained  by  dividing 
the  bending  moment  by  the  unit-stress.  This  beam  will  be  the  beam 
which,  with  a  unit-stress  equal  to  the  one  assumed,  will  withstand  the 
bending  moment  under  consideration. 

The  handbooks  issued  by  many  of  the  steel  companies  are  indis- 
pensable to  the  intelligent  design  of  structural  steel.  That  issued  by 
the  Carnegie  Steel  Company  (edition  of  1903)  is  one  of  the  most  con- 
venient; and  since  it  will  be  frequently  referred  to  in  this  text,  its 
purchase  by  the  student  is  desired.  This  book  may  be  obtained  by 
addressing  the  Carnegie  Steel  Company  at  its  offices  in  any  of  the 
larger  cities.  The  cost  to  students  has  usually  been  50  cents;  to 
others,  $2.00. 

Assuming  an  allowable  unit-stress  of  18  000  pounds  per  square 
inch  on  the  extreme  fibre,  the  section  modulus  required  to  withstand 
the  bending  moment  of  111  360  pound-inches  is: 
in  360 
-18-000  -6-19' 

Looking  in  the  Carnegie  Handbook  at  column  11  on  page  100, 
column  11  on  page  102,  and  column  9  on  page  104,  it  will  be  seen  that 
any  one  of  the  following  shapes  will  be  sufficient: 

One  5-inch  14.75-pound  I-beam; 

One  7-inch    9.75      "       channel; 

One  4i  by  3T%  by  T9ff-inch  Z-bar  weighing  17.9  pounds  per  linear  foot. 


138 


ROOF  TRUSSES  17 

Instead  of  the  5-inch  I-beam  as  given  above,  a  6-inch  12.25- 
pound  I-beam  with  a  section  modulus  of  7 . 3  could  be  used,  and  would 
be  more  economical,  since  it  is  less  in  weight;  and  it  would  also  be 
stiffer,  since  its  depth  is  greater  and  its  section  modulus  is  greater.  A 
comparison  of  the  above  weights  shows  the  channel  to  be  the  most 
economical,  since  its  weight  is  considerably  less  than  either  of  the 
other  two  shapes.  Channels  usually  make  the  most  economical  pur- 
lins; and  for  this  reason  no  other  shapes  are  usually  inspected,  the 
channels  being  used  in  the  first  case  without  being  compared  with 
other  sections.  Inspection  of  column  11,  page  110,  Carnegie  Hand- 
book, shows  that  a  6  by  4  by  f-inch  angle  could  have  been  used  for  the 
purlin,  since  it  gives  a  section  modulus  of  6.25.  The  weight  of  this 
angle,  23.6  pounds  per  linear  foot,  shows  it  to  be  far  too  uneconomical 
to  employ. 

EXAMPLES    FOR    PRACTICE 

1.  Design  the  rafters  when  the  total  weight  of  the  snow  and  roof 
covering  is  30  pounds  per  square  foot,  and  the  purlins  are  spaced  15  feet  apart. 
Use  1  000  pounds  per  square  inch  as  the  allowable  unit-stress. 

2.  Design  the  purlins  if  the  trusses  are  12  feet  center  to  center;  the 
purlins  are  spaced  8  feet  apart;  the  roof  covering,  which  weighs  6  pounds  per 
square  foot,  is  laid  upon  1-inch  yellow  pine  sheathing  resting  directly  upon 
the  purlins;  and  the  snow  load  is  10  pounds  to  the  square  foot  of  roof  surface. 
Use  18  000  pounds  per  square  inch  as  the  allowable  unit-stress,  and  use  a 
ohannel  for  the  purlin  section. 

7.  Bracing.  In  order  to  keep  the  roof  trusses  erect,  bracing 
is  employed  to  join  together  their  top  chords  and  also  their  bottom 
chords.  This  bracing  may  consist  either  of  small  round  or  square 
rods,  or  it  may  consist  of  angles.  The  latter  is  the  best  practice, 
since  it  gives  great  rigidity  to  the  structure;  and  in  fact  it  should  be 
used  in  all  cases  where  machinery  of  any  kind  is  attached  to  the 
trusses.  One  disadvantage  of  the  rod  bracing  is  that  good  connec- 
tions with  the  trusses  are  usually  difficult.  The  bracing  between 
the  lower  chords  is  lighter  than  that  between  the  top  chords,  since 
its  office  is  merely  to  prevent  vibration,  while  that  between  the  upper 
chords  must  take  up  the  stresses  caused  by  the  wind  blowing  upon  the 
ends  of  the  building.  The  stresses  in  each  of  these  classes  of  bracing 
can  only  be  approximately  determined;  and  for  that  reason  it  has 
become  customary  to  determine  their  section  by  judgment  Bather 
than  by  computation.  For  lower  chord  bracing,  single  angles  3  by 


18 


ROOF  TRUSSES 


2  by  y^-inch  are  recommended;  and  for  upper  chord  bracing,  3  by 

3  by  T5s-inch  angles  should  be  used. 

It  is  not  customary  to  place  bracing  between  each  pair  of  trusses, 
but  to  place  them  between  each  alternate  pair  or  between  every  third 
pair  of  trusses.  Fig.  23  shows  several  ways  in  which  the  bracing  may 
be  inserted. 

8.  Economical  Spacing  and  Pitch  of  Trusses.  The  term  pitch 
which  has  been  used  in  the  preceding  pages  is  the  fraction  obtained  by 
dividing  the  span  into  the  height  of  the  truss  at  the  center  of  the 

span.  For  example,  if  a  truss  has 
a  span  of  60  feet,  and  a  rise  of  12 
feet  at  the  center,  it  would  be 
said  to  have  a  pitch  of  ^;  if  the 
rise  were  15  feet,  the  pitch  would 
be  |;  and  if  the  rise  were  20  feet, 
the  pitch  would  be  £.  The  pitch 

Upper  Chord  Bracing  r  .  r 

of  a  truss  is  seldom  expressed  in 

degrees  by  giving  the  angle  that 
the  top  chord  makes  with  the 
horizontal.  One  exception  is 
very  common.  It  is  to  use  the 
30°  pitch.  This  has  the  advan- 
tage of  making  the  height  of  the 
center  equal  to  one-half  the  length  of  one  side  of  the  top  chord — a 
fact  which  lends  itself  to  ease  in  making  the  shop  drawings. 

The  maximum  or  minimum  allowable  pitch  for  any  given  roof 
depends  to  a  great  extent  upon  the  class  of  roof  covering  employed. 
For  pitches  required  for  any  given  class  of  roof  covering,  see  Article 
5,  p.  6.  It  might  be  noted  that  most  of  the  patent  roofings,  or  any 
roofing  in  which  tar  or  asphalt  is  an  ingredient,  should  not  be  laid 
upon  roofs  with  a  pitch  greater  than  ^  or  £;  while  most  of  the  cover- 
ings which  consist  of  steel  or  clay  products  require  pitches  of  £  or  over. 
Pitches  varying  from  i  to  ^  have  very  little  effect  upon  the  weight 
of  the  trusses.  This  is  true  only  for  trusses  with  horizontal  lower 
chords.  If  the  lower  chord  is  cambered — that  is,  raised  above  the 
horizontal  position — it  greatly  increases  the  stresses  in  the  truss,  and 
consequently  the  weight  of  the  truss.  The  greater  the  camber,  the 
greater  the  weight  of  the  truss,  the  pitch  remaining  the  same.  If  the 


Looking  Upward -The  Lower  Chord  Bracing 

Fig.  23.    Methods  of  Inserting  Bracing 
between  Trusses. 


140 


ROOF  TRUSSES  19 

camber  is  constant,  then  the  greater  the  stresses  (and  consequently 
the  weight  of  the  truss),  the  smaller  the  pitch.  It  is  advisable  not  to 
camber  the  lower  chord  unless  it  is  positively  necessary.  A  camber  of 
5  per  cent  of  the  span  will  increase  the  weight  of  the  truss  from  10  to 
40  per  cent,  according  to  the  pitch. 

Taking  all  things  into  consideration,  a  pitch  of  J  or  ^  is  to  be 
preferred  over  that  of  |  or  less,  since,  after  the  pitch  becomes  less 
than  I-,  the  weight  of  the  truss  increases  quite  rapidly,  the  span  being 
constant. 

For  any  given  roof,  there  is  an  economical  spacing  of  the  trusses. 
As  the  spacing  of  the  trusses  increases,  the  weight  of  the  purlins  and 
bracing  per  square  foot  of  area  increases,  while  the  weights  of  the 
trusses,  the  columns  that  support  them,  and  the  girts,  or  members 
which  run  from  one  column  to  the  other  and  on  which  the  siding  of  the 
building  is  placed,  decrease.  The  most  economical  spacing  of  the 
trusses  is  such  as  will  make  the  cost  of  the  above  quantities  a  mini- 
mum. It  is  evident  that  this  spacing  for  trusses  which  rest  upon 
masonry  supports  will  be  different  from  the  spacing  in  case  they  rest 
upon  steel  columns.  Attention  is  called  to  the  statement  that  the 
sum  of  the  costs,  instead  of  the  sum  of  the  weights  of  the  above- 
mentioned  quantities,  should  be  a  minimum.  This  is  due  to  the  fact 
that  the  unit-cost  of  the  purlins  is  considerably  less  than  that  of  the 
trusses,  it  being  in  some  cases  only  about  one-half. 

The  spacing  of  trusses  is  sometimes  governed  by  local  conditions, 
such  as  the  placing  of  the  machinery  in  the  building  and  the  probable 
position  of  future  additions.  Considering  the  spacing  from  a  purely 
economical  standpoint,  it  is  probably  well  to  space  trusses  about  as 
indicated  in  Table  V. 

TABLE  V 
Spacing  of  Trusses 


SPAN,  IN  FEET                     SPACING,  IN  FEET 

10  to  30 

12 

30  to  60 

15 

60  to  75 

20 

75  to  150 

21  to  25 

The  spacing  indicated  in  Table  V  is  for  triangular  roof  trusses  of  equal  size 
and  span.     For  other  conditions — such  as  when  the  main  roof  consists  of 


141 


20  ROOF  TRUSSES 

one  span,  and  the  side  roofs  consist  of  different  spans  and  different  classes  of 
trusses — the  economical  spacing  may  be  somewhat  different,  and  is  usually 
less. 

The  best  method  of  determining  the  economical  spacing  is  either 
to  make  a  comparative  design  or  to  consult  the  back  volumes  of 
The  Engineering  Record,  Engineering  News,  or  some  other  good 
engineering  periodicals.  Designs  of  buildings  which  have  been  con- 
structed are  frequently  given  in  these  periodicals;  and  from  these  the 
student  may,  in  addition  to  the  spacing  of  the  trusses,  obtain  much 
other  valuable  information  regarding  roof  construction. 

Bulletin  No.  16  of  the  University  of  Illinois  Experiment  Station 
gives  a  systematic  study  of  roof  trusses,  and  shows  the  effect  on  the 
variation  in  the  weights  of  rafters  and  purlins  due  to  a  variation  in  the 
length  of  span.  This  bulletin,  which  can  be  had  free  for  the  asking, 
should  be  in  the  hands  of  the  student.  It  may  be  had  by  addressing 
"The  Director,"  Engineering  Experiment  Station,  University  of 
Illinois,  Urbana,  Illinois.  A  most  valuable  book  giving  a  systematic 
and  extensive  study  of  roof  trusses  and  mill  buildings,  is  "Steel  Milt 
Buildings,"  by  M.  S.  Ketchum,  Engineering  News  Publishing  Com- 
pany, New  York,  N.  Y. 

9.  Stresses  in  Roof  Trusses,  and  Sizes  of  Members.  Stresses  in 
roof  trusses  of  any  form  can  be  computed  by  the  methods  of  "Statics" 
(pp.  23  to  73).  On  account  of  the  ease  and  economy  of  manufacture, 
some  form  of  truss  is  usually  used  in  which  there  are  many  members 
with  equal  stresses.  The  Fink  truss,  or  some  modification  of  it,  is 
almost  universally  used  (see  Fig.  l,c,d,  e,  /).  On  pages  21  and  22  are 
shown  some  forms  of  trusses,  together  with  the  pitches  which  are 
commonly  used. 

The  stresses  in  the  various  members  due  to  a  vertical  panel  load 
of  one  pound  are  given.  To  obtain  the  stress  in  that  member  due 
to  any  other  vertical  panel  load,  multiply  the  stress  here  given  by  the 
vertical  panel  load. 

For  example,  if  the  stresses  in  U^  (Fig.  24)  or  L^  (Fig.  31) 
due  to  a  panel  load  of  3  000  pounds,  were  required,  they  would  be 
determined  as  follows: 

U2  L3  (Fig.  24)     3  000  X  -  1 . 73  =   -  5  190  pounds. 
L0  Lt  (Fig  31)     3  000  X  +  5.00  =   + 15  000  pounds 

These  diagrams  are  especially  useful,  since  it  is  the  custom  of 
many  engineers  not  to  compute  the  stresses  due  to  wind,  snow,  and 


142 


ROOF  TRUSSES 

T 


21 


Fig.  30.  Fig.  31. 

Analysis  of  Stresses  in  Various  Members  of  Fink  Truss  Due  to  Unit-Loads. 


143 


22 


ROOF  TRUSSES 


Fig.  32. 


Fig.  33. 


k  Pitch 


Fig.  34. 


Fig.  35. 


Angle  30 


Fig.  36. 


k  P'tch 


Fig.  37.  Fig.  38. 

Analysis  of  Stresses  in  Various  Members  of  Fink  Truss  Due  to  Unit-Loads. 


144 


ROOF  TRUSSES  23 

dead  weight  of  roof  trusses  and  coverings,  but  to  compute  the  stresses 
due  to  a  dead  panel  load  caused  by  40  pounds  per  square  foot  of 
horizontal  projection.  The  stresses  resulting  from  this  procedure 
are  very  nearly  equal  to  those  produced  by  considering  the  various 
loads  —  as  snow,  dead  load,  and  wind  —  separately  or  together.  When- 
ever differences  occur,  they  are  on  the  safe  side,  except  as  noted  below, 
and  in  the  next  article,  in  case  of  the  stresses  produced  by  the  use  of 
knee-bracing. 

The  panel  load  to  be  used  when  40  pounds  per  square  foot  of 
horizontal  projection  is  considered,  may  be  computed  from  the  formula  : 

p  =  40  X  a  X  I 

n 
in  which, 

a=  Distance  between  trusses,  in  feet; 

I  =  Span  of  truss,  in  feet; 

n  =  Number  of  panels  in  top  chord  of  truss. 

For  example,  let  it  be  required  to  compute  the  panel  load  P  for 
the  truss  of  Fig.  24  when  the  span  is  70  feet  and  the  distance  between 
trusses  is  16  feet.  Here  a  =  16;  I  =  70;  and  n  =  8. 


The  truss  would  then  be  computed  for  a  vertical  panel  load  of  5  600 
pounds,  and  the  members  designed  to  withstand  the  stresses  thus 
obtained. 

This  method  is  applicable 
to  all  spans  up  to  100  feet  when 
the  truss  is  set  on  masonry  walls 
(or  steel  columns  built  in  mason- 
ry walls)  and  the  roof  covering  is 
of  corrugated  steel  or  any  of  the 
ordinary  materials.  Where  clay 
tile  or  slate  are  used,  50  pounds 
should  be  taken;  and  in  case  of 

concrete  slabs,  65  pounds  would  be  about  right.  It  is  better  practice 
to  compute  the  stresses  due  to  wind,  snow,  and  dead  loads  when 
clay  tile,  slate,  or  concrete  are  used. 

In  cases  where  the  roof  truss  is  placed  on  steel  columns  and  is 
connected  with  the  column  by  a  knee-brace  at  the  first  joint  (see 
Fig.  39),  stresses  caused  by  the  overturning  action  of  the  wind  take 


145 


24 


ROOF  TRUSSES 


place  in  those  members  shown  by  heavy  lines.  In  this  case  the 
stresses  caused  by  40  pounds  per  square  foot  of  horizontal  projec- 
tion are  not  large  enough;  but  the  truss  will  be  safe  enough  if  the 
stresses  as  determined  by  the  40  pounds  are  increased  by  the 
amounts  indicated  in  Fig.  39. 

For  example,  let  the  truss  of  Fig.  24  be  supported  by  steel  columns 
and  knee-bracing.  Let  the  span  be  60  feet,  and  the  distance  between 
trusses  16  feet;  and  let  it  be  required  to  compute  the  stresses  in  L^ 
U2  and  L3  C74.  Here  P=  (40  X  16  X  60)  -=-  8  -  4  800,  and  the  stresses 

will  be: 

L!  U2   (0 . 87  X  4  800)  X  2 . 10  =  +   8  770  pounds. 
L3  U4    (2  .60  X  4  800)  X  1 .50  =  +18  700  pounds. 

In  addition  to 
the  above  condi- 
tions, shafting, 
heating  appara- 
tus, small  cranes, 
and  electric  wir- 
ing and  other  con- 
ductors are  often 
attached  to  the 
lower  chord  of  the 
truss.  These  cause 
additional  stress- 
es. The  case  is 
that  of  a  concen- 
trated load  or 
loads  at  the  lower 
chord,  and  the 
stresses  may  be 
computed  by  the 
methods  given  in 
"Statics." 

For  example,  let  a  5-ton  hoist  be  connected  as  shown  in  Fig.  40 
This  hoist  runs  longitudinally  of  the  shop,  or  perpendicularly  to  the 
plane  of  the  roof  truss.  The  maximum  stress  in  the  truss  due  to  this 
cause  will  occur  when  the  hoist  is  directly  beneath  the  truss.  The 
stresses  will  be  those  caused  by  a  load  of  10  000  pounds  at  the  second 
panel  point  of  the  lower  chord.  Fig.  40  gives  the  stress  diagram  for 


Fig.  40.    Fink  Truss  Loaded  with  5-Ton  Hoist ;  also 
Stress  Diagram  of  Same. 


146 


ROOF  TRUSSES 


25 


TABLE  VI 
Hoist  Stresses  in  Fink  Truss 


Member 

Stress 

Member 

Stress 

LoL/4- 

-15  350 

LzU4- 

+  IZ500 

LoLz 

+  13700 

U4L'o 

-  6900 

L'z  L'o 

+  6  100 

All  Others 

0 

this  condition,  and  Table  VI  gives  the  stress  record.  From  this  it  is 
seen  that  the  hoist  does  not  affect  all  members  of  the  truss.  The 
stresses  due  to  the  hoist  should  be  added  to  those  caused  by  the  40 
pounds  per  square  foot  of  horizontal  projection,  and  the  member 
designed  accordingly.  Of  course,  if  the  stress  caused  by  the  hoist 
decreases  the  stress  caused  by  the  40  pounds,  the  member  must  be  de- 
signed for  the  stress  due  to  the  40  pounds. 

Note  that  concentrated  loads,  as  in  the  case  of  the  hoist,  cause 
different  stresses  in  symmetrical  members  on  the  two  sides  of  the 
truss.  In  the  final  design,  the  members  are  made  the  same,  being 
designed  for  the  greatest  stress.  This  is  done  for  the  sake  of  economy 
in  manufacture;  and  besides,  it  might  be  desirable  to  change  the 
hoist  to  the  other  side  of  the  truss. 

For  Fink  trusses  with  pitches  of  from  ^  to  ^,  and  spans  of  less 
than  100  feet,  very  light  angles  are  usually  required  for  the  members, 
unless  heavy,  concentrated  loads  are  placed  on  the  lower  chord.  The 
thickness  of  the  connection  plates  is  seldom  more  than  f  inch,  the  top 
chord  angle  seldom  greater  than  5  by  3^-inch,  the  lower  chord  angle 
seldom  greater  than  3  by  3-inch;  and  the  web  members  are  usually 
composed  of  angles  either  2  by  2-inch  or  1\  by  2^inch.  It  appears 
to  be  the  rule,  in  present  practice,  to  make  the  sizes  such  that  the 
thickness  shall  be  \  or  T\  inch'.  Connection  plates  for  spans  up  to 
60  or  70  feet  are  usually  \  inch  thick,  except  in  the  case  of  that 
at  point  L0. 

The  stresses  in  knee-braces  depend  upon  the  height  and  also  the 
width  of  the  building.  The  stresses  may  be  computed  according  to 
the  methods  of  the  next  article,  and  the  knee-bracing  should  be 


147 


26  ROOF  TRUSSES 

designed  accordingly.  The  inspection  of  a  number  of  plans  seems  to 
indicate  that  the  sizes  of  knee-braces  vary  from  two  angles  2^  by  2^ 
by  J-inch  for  spans  of  30  feet  and  a  height  of  building  of  35  feet,  to 
two  angles  4  by  3  by  T\-inch  for  a  span  of  70  feet  and  a  height  of 
building  to  the  top  of  the  truss  of  75  feet. 

In  case  of  roof  trusses  with  the  chords  nearly  parallel  (see  Fig. 
3,  p.  2),  the  stresses,  on  account  of  the  small  depth,  are  usually 
quite  large,  and  much  heavier  members  than  above  mentioned  are 
required.  In  some  cases,  6  by  6-inch  angles  with  8-inch  plates  are 
used,  and  connection  plates  of  f  to  \  inch  are  common. 

In  cases  where  the  trusses  are  subjected  to  the  action  of  corrosive 
gases,  the  thickness  of  the  members  should  be  made  greater  than  that 


OIL 

Fig.  41.  Bending  Tendency,  Ends  Free.    Fig.  42.  Bending  Tendency,  Ends  Fixed. 

required  by  the  design  alone,  since  corrosion  will  decrease  the  section 
considerably,  and  this  should  be  allowed  for. 

10.  The  Steel  Truss=Bent.  When  a  truss  is  connected  to  steel 
columns  at  its  ends  and  by  means  of  knee-bracing  (see  Fig.  39),  it 
forms  what  is  called  a  steel  truss-bent.  The  stresses  in  the  truss 
due  to  the  roof  covering  and  snow  loads  are  the  same  as  when  it  is 
supported  by  a  masonry  wall ;  but  the  wind  stresses  are  different.  The 
wind  blowing  on  the  roof  and  also  on  the  sides  of  the  building,  causes 
stresses  in  the  truss.  The  wind  on  the  building  is  transferred  to  the 
columns,  which,  by  means  of  the  knee-braces,  cause  stresses  in  the 
truss.  The  whole  bent  tends  to  bend  as  shown  in  Fig.  41  if  the  ends 
cf  the  columns  rest  on  masonry  pedestals.  If  the  ends  of  the  columns 
are  securely  bolted  to  heavy  masonry  pedestals  so  that  the  ends  of 
the  post  will  remain  vertical,  they  will  tend  to  bend  as  shown  in  Fig. 
42.  In  the  first  case,  the  overturning  is  resisted  by  the  bending  of  the 
post  as  shown  at  b  and  b'  (Fig.  41);  in  the  second  case,  by  bending  as 
at  b,  c,  bf,  and  c'  (Fig.  42).  Since  the  post  is  the  same  size  throughout, 
and  the  bending:  caused  by  the  wind  the  same  in  both  cases,  the  bend- 


148 


ROOF  TRUSSES 


27 


v, 


Pig.  43.    Notation  for  Formulae,  Ends  Free. 


ing  moment  in  the  post  at  b  and  b'  (Fig.  42)  is  less  than  it  is  at 
b  and  b'  (Fig.  41),  as  in  the  first  case  there  are  only  one-half  the  num- 
ber of  points  to  withstand  the  total  bending  that  there  are  in  the 
second  case. 

The  wind  blowing  on  one  side  of  the  building  causes  a  compres- 
sive  stress  in  the  column  on  the  leeward  side  (the  side  opposite  that  on 
which  the  wind  blows)  and  a  tensile  stress  in  the  column  on  the  wind- 
ward side  (the  same  side  on  which  the  wind  blows).  It  also  creates  a 
bending  moment  as 
men  tioned  above ; 
and  this,  as  well  as 
the  direct  stresses, 
must  be  taken  into 
account  when  the 
post  is  designed. 
The  case  is  that  of 
a  member  under 
direct  compression 
and  bending  at  the 
same  time. 

The  stresses  in 
the  knee-braces  and 
the  columns,  and  the  bending  in  the  columns  when  the  ends  of  the 
posts  are  not  fixed,  may  be  computed  from  the  following  formulae,  in 
which, 

W    =  Total  wind  load  perpendicular  to  the  roof; 

W^  =  Horizontal  component  of  W; 

Wv  =  Vertical  component  of  W; 

Wl   =  Total  wind  load  on  the  side  of  the  building; 

w    =  Unit  wind  load  normal  to  the  roof; 

Wt   =  Unit  wind  load  normal  to  the  side  of  the  building; 

a    =  Distance  between  trusses,  in  feet. 

These  and  other  characters  are  shown  in  Fig.  43. 


W    =  wa^r 
Wx  =  «>!  ah 


149 


28  ROOF  TRUSSES 


W,      +  Wh  (h  +  - 


«•- 


Bending  moment  at  &  =  Hln  —  Wl  (-^  —  m) 
Bending  moment  at  6'  =  H2  n. 

The  stresses  in  the  truss  caused  by  the  wind  are  the  same  as  if 
it  were  under  the  action  of  the  normal  wind  load  W,  and  in  addition 
two  concentrated  loads  equal  in  intensity  and  direction  to  the  stresses 
in  the  knee-braces  and  at  the  same  point  of  application,  and  two 

forces  Ei  and  E2,  which  may  be 
computed  as  follows: 

E  ^H.n 
1 


Fig.  44.    Application  and  Direction  of  the  7?  _ 

eir   ores. 


For  the  points  of  application  for  these  loads  and  for  their  direction, 
see  Fig.  44.  The  stresses  can  now  be  computed  by  the  method  of 
Statics. 

The  diagram  for  such  a  truss-bent  is  given  in  Fig.  45.  The  span 
is  60  feet,  the  rise  |,  the  distance  between  trusses  16  feet;  and  the 
wind  pressure  is  taken  as  18  pounds  per  square  foot  normal  to  the 
roof  surface,  and  20  pounds  per  square  foot  normal  to  the  sides. 
In  this  case,  w  =  18  pounds;  a  =  16  feet;  r  =60  -r-  4  =  15  feet;  w  = 
20  pounds;  h  =  20  feet;  n  =  14  feet;  m  =  6  feet;  and  Z  =  60  feet. 
The  length  of  L0U4  is  readily  computed  to  be  33.5  feet;  L0  Lv  9.1  feet; 
and  e  =  5  feet.  The  values  of  the  quantities  and  stresses  are  com- 
puted as  follows  (see  Fig.  46) : 

W    =  18  X  16  V302  +  152  =  9  650  pounds. 

Wi  =  16  X   20  X  20  =  6  400  pounds. 

TTh  =  (9  650  -T-  33.5)  X  15  =  4  320  pounds. 

W-  ^  (q  650  -5-33.5)  X  30  =  8  650  pounds. 

Xi  =  #2  =  (4  320  +  6  400)  -5-  2  =  5  360  pounds. 


150 


ROOF  TRUSSES 


29 


=   + 


5360  X  20-6400  X  10 


+  8  640  pounds. 


0  5  360  X  20 

<Sa'b'  = 5 =  -  21  440  pounds. 

o 

Sl-       536°6X14=  12  520  pounds. 
5360  X  14 -6  400  X  4 


6 

The  horizontal  and  vertical  components  of  the  stresses  in  the 

knee-bracing  should 

now  be  computed. 

&t> 

T^°         \ 

They  are:                                           r*f 
ifcXO      \ 

Arw 

For  ab  :  horizon-              «&       \J^y 

^fey      XJP^X' 

\   5  /       8         \  |,    /V^ 

tal,    7240;     vertical,    8240    B  V^V4 

V            \/^NS^  na 

4  760  pounds. 

^          Y           H 

^  c 

For    a'  6'  :    hori- 

s" 

zontal,  17  900;    verti- 

cal, 11  800  pounds. 

i            i 

14-13 


As  a  check  upon 
the  computations, 
the  sum  of  the  val- 
ues of  Ev  E2,  and 
TFh  should  be  equal 
to  the  sum  of  the 
horizontal  compo- 
nents of  the  knee- 
braces.  By  sum- 
ming Up  the  above  Fig  45<  stress  Diagram  of  Truss-Bent  under  Wind  Load. 

values,    it   will    be 

seen  that  they  check  by  80  pounds,  which  is  less  than  0 . 4  of  one  per 

cent  and  is  a  close  enough  check  (see  Figs.  46  and  47). 

To  obtain  the  vertical  reactions,  proceed  as  with  a  simple  truss. 
For  R2,  take  the  center  of  moments  at  L0  (see  Fig.  47).    Then: 

R2  =  J_.J8650  X  15  +  4320  X  7.5  +  4760  X  9.1 -11  800  X  (60-  9.1)} 

=   —  6  514  pounds. 

The  negative  sign  indicates  that  the  reaction  acts  downward;  that  is, 
the  truss  must  be  riveted  to  the  post  at  Ls,  or  the  end  of  the  post 
would  be  lifted  off  the  top  of  the  column. 


151 


30 


ROOF  TRUSSES 


For  Rv  the  center  of   moments  is  at    L8,  and  the  resulting 
equation  is: 
Ri  =  _L«  _n  800X9.1  +  8650(60  -  15) -4  320  X  7.5  +  4760(60-9.1)} 

=  +8  180  pounds. 
The  bending  moment  at  b  is: 

Afb  =  14  X  5  360  -  4  X  6  400  =  49  440  pound-feet; 

and    the    bending 
moment  at  6' is: 

M  b«  =  5  360  x  14 
=75  040  pound-feet. 

The  forces  in 
their  proper  di- 
rection are  now 
placed  on  a  dia- 
gram of  the  truss 
(Fig.  47),  and  the 
stresses  are  solved 
by  the  method  of 
Statics.  The  stress 
diagram  is  given 
in  Fig.  45,  and  the 
stress  record  in 
Table  VII. 

The  above  for- 
mulie  are  for  cases 
when  the  columns 
are  free  at  the 
lower  end.  When 
the  columns  are 
not  free,  they  are 
called  fixed-,  that 
is,  they  are  sup- 
to  be  so 


Fig.  46.    Position,  Direction,  and  Intensity  of  Wind  Forces, 
Ends  Free. 


Fig.  47.    Position,  Direction,  and  Intensity  of  Exterior  Forces. 


tightly  connected  that  they  cannot  move  when  the  post  bends  as 
shown  in  Fig.  42.  In  such  cases  the  result  is  the  same  as  if  the 
columns  were  shortened  by  an  amonut  n  -s-  2,  and  the  following 
formulae  result  (see  Fig.  48) : 


152 


ROOF  TRUSSES 


31 


TABLE  VII 
Stress  Record  of  Truss=Bent  under  Wind  Load 


Member 

Stress 

Member 

Stress 

X-2 

-15  700 

9-10,11-12 

-f  6  500 

X-3 

-15  700 

12-13,14 

-15  300 

X-6 

-10  700 

Y-4 

+   6  500 

X-7 

-10700 

Y-8 

-    1  900 

X-9 

-f-    1  500 

Y-IZ 

-  9  600 

X-13 

-H5400 

13,14-15 

-    1  300 

1-2 

+    5  ZOO 

I-Y 

+   8640 

2-3 

-    2410 

15-Y 

-2  1  440 

3-4 

+  a  500 

A-l 

-  8  180 

4-5 

-    7  500 

C-15 

+  6  514 

5-6 

+    2  700 

b-c 

-  3457 

6-7 

-    2410 

b'-c' 

-  5  193 

7-8 

+  II    000 

9-IO-JI 

0 

8-9 

-   7  600 

13-14 

0 

W  =  wa^jr2  +  (~Y 

.    n  -, 


. 


<Sa'b'=  — 


153 


32  ROOF  TRUSSES 


Bending  moment  at  b  =  Mb  =  H1  -=•  — TF,  (— =- 


-  4 


Bending  moment  at  b'  =  Mb>  =  H2  — . 


For  the  truss-bent  of  Fig.  45,  when  the  columns  are  fixed  at  the 
base,  the  stresses  are  the  same  as  if  the  columns  were  shortened  by  an 
amount  n  -r-  2,  as  above  mentioned.  The  bent  would  then  appear  as 
in  Fig.  49,  and  the  values  of  the  various  stresses  and  the  quantities, 
together  with  their  points  of  application,  are : 

W    =  18  X  16\/302+  152  =  9  650  pounds,  as  before. 
Wl  =  13  X  16  X  20  =  4  160  pounds. 

_         _  4  160  +  4  320  _      24Q    ounds 

2 
^  =    +  4  240X13 -4  160X6.5  =    f5616pounds. 

&.„.•  -424°x13=_11  024  pound, 

o 

.  4  160  X  7  +  4  320  X  20.5  -  8  650  X  45 
Sbc  =  H — gQ —          = —4  526  pounds. 

4  160  X  7  +  4  32Q  X  20.5  +  8  650  X  15 
SbV=  -  gQ -  =  —4  124  pounds. 

Et  =   4  24°g  X  7  =  4  947  pounds. 

E      4  240  X  7  -  4  160  X  0 . 5  _ 

6 

Afb   =        4  240  X  7  -  4  160  X  0.5  =  27  600  pound-feet. 
Mi/  =        4  240  X  7  =  29  680  pound-feet. 

The  stresses  in  the  bent  are  then  computed  in  a  manner  similar 
to  that  used  when  the  columns  are  fixed,  Ev  E2,  and  the  stresses  in 
the  knee-braces  being  attached  to  the  truss  as  concentrated  loads. 

Since  in  this  case,  Ev  E2,  and  the  stresses  in  the  knee-braces  are 
less  than  they  are  when  the  columns  are  free  at  the  base,  the  wind 
stresses  throughout  the  truss  will  be  less  when  the  columns  are  fixed 
than  when  they  are  free. 

On  account  of  the  difficulty  of  fixing  the  ends  rigidly,  it  is  advis- 
able always  to  consider  the  ends  free  and  to  compute  the  stresses 
accordingly. 

The  student  is  advised  not  to  take  the  trouble  of  determining 


154 


CHICAGO  SERVICE  BUILDING  OF  FORD  MOTOR  COMPANY,  SHOWING  MODERN 
CONCRETE  CONSTRUCTION 

The  roof  trusses  are  of  concrete,  and  flat-slab  floor  construction  is  used  throughout. 
Courtesy  of  the  Condron  Company,  Chicago 


ROOF  TRUSSES 


33 


the  wind  stresses  in  trusses  of  steel  truss-bents  by  the  method  given 
above,  but  to  use  the  40  pounds  per  square  foot^of  horizontal 
projection  and  to  correct  the  stresses  as  previously  mentioned  (see 
Fig.  39). 

The  formulae  of  this  article  giving  the  stresses  in  the  knee- 
bracing  and  the  bending  moment  in  the  columns,  should  be  used  in 
all  cases,  and  the  posts  and  knee-braces  designed  according  to  the 
stresses  so  determined. 

In  cases  where  the  40  pounds  per  square  foot  is  used,  the  direct 
stress  in  each  column  is: 


S  = 


40  X  a  X  I 


Fig.  48.    Notation  for  Formulas, 
Ends  Fixed. 


and  the  column  should  be  de- 
signed for  this  stress,  together 
with  the  stress  due  to  the  bend- 
ing at  the  point  where  the  knee- 
brace  joins  the  column.  See 
"Strength  of  Materials,"  pp.  85 
and  86. 

In  case  a  crane  is  attached 
to  either  the  truss  or  the  column, 
the  stresses  due  to  its  action  must 
be  considered  in  the  design. 

11.  Suspended  Loads.  Un- 
der this  head  come  any  loads 
which  may  be  suspended  from 
the  lower  chord  of  the  truss. 
The  load  may  not  be  actually 
suspended  from  the  underneath 
part,  but  may  be  placed  above, 

and  the  connections  so  arranged  as  to  bring  the  weight  on  the 
lower  chord.  This  weight  should  preferably  be  concentrated  at 
a  panel  point.  In  case  it  cannot  be  brought  directly  to  the  panel 
point,  it  may  be  distributed  over  a  portion  or  all  of  the  panel.  In 
this  case  the  portions  distributed  to  the  adjacent  panel  points  are 
computed,  and  they  are,  for  purposes  of  computation,  considered  as 
concentrated  loads  at  the  panel  points.  The  sections  of  the  chord 
over  which  these  loads  are  distributed  are  in  the  condition  of  direct 


Fig.  49.    Position,  Direction,  and  Intensity 
of  Wind  Forces,  Ends  Fixed. 


155 


34 


ROOF  TRUSSES 


tension  and  bending,  and  must  be  designed  for  such  stresses  (see 
"Strength  of  Materials,"  pp.  85  and  86). 

The  suspended  loads  may  consist  of  small  hand  cranes;  shafting 
for  transmission  of  power;  heating  apparatus,  such  as  steam  or  hot-air 
pipes ;  water  or  compressed-air  tanks ;  or  platforms  on  which  stand  the 
operators  for  the  cranes  or  hydraulic  lifts.  Figs.  50  and  51  show 

trusses  with  vari- 
ous forms  of  sus- 
pended loads  at- 
tached. 

12.  Details  of 
Roof  Trusses. 
The  spans  of  tri- 
angular roof  truss- 
es of  the  Fink  type 
are  usually  less 
than  100  feet,  and 
the  spans  of  roof 
trusses  with  chords 
nearly  horizontal 
are  seldom  greater 
than  50  feet.  For 
trusses  of  such 
spans  the  details 
are  almost  stand- 
ard. Since  these 
spans  and  trusses 
constitute  a  large 
majority  of  those 

built,  only  the  details  of  such  trusses  will  be  considered  in  this  text. 
Where  trusses  rest  on  masonry  walls  or  on  light  columns  in 
masonry  walls,  provision  is  made  for  expansion  due  to  temperature. 
For  trusses  up  to  75  or  80  feet,  slotted  holes  are  placed  in  the  end- 
bearing,  and  the  bearings  rest  directly  upon  another  plate.  Bolts 
are  fastened  to  the  masonry,  and  extend  upward  through  the  slotted 
holes  and  have  nuts  on  their  ends.  The  nuts  hold  the  truss  securely 
to  the  wall,  while  the  slotted  holes  allow  the  bearing  to  move  backward 
and  forward  when  the  temperature  falls  or  rises.  The  slotted  holes 


Fig.  61. 
Various  Kinds  of  Suspended  Loads. 


156 


ROOF  TRUSSES 


35 


should  be  |  inch  in  length  for  every  ten  feet  of  span.  The  bolts  should 
not  be  less  than  \  inch  in  diameter,  and  should  be  buried  in  the 
masonry  at  least  6  inches.  Fig.  52  shows  details  of  an  expansion 
bearing  of  this  character.  In  case  the  span  of  the  truss  is  greater 
than  75  or  80  feet,  a  roller  or  a 
rocker  bearing  is  used.  Figs.  53 
and  54  show  details  of  this  class 
of  bearings. 

For  convenience  in  refer- 
ences to  the  common  Fink  truss, 
the  following  notation  will  be 
used:  the  points  in  the  upper 
chord  are  given  the  letter  U,  with 
a  subscript  corresponding  to  the 
number  of  the  joint  from  the  left 
end.  The  lower  chord  and  in- 
terior joints  are  given  the  letter 

L,  with  a  subscript  correspond-  2e  .  Allowance  for  Expansion 
ing  to  the  number  of  the  joint 
from  the  left  end  (see  Figs.  24  to 
38).  The  advantage  of  this  system  of  notation  is  that  it  enables 
one  to  refer  to  any  particular  joint  by  the  use  of  the  letter  and  its 
subscript,  and  its  position  will  at  once  be  apparent  to  the  mind 

without  the  use  of  a  fig- 
ure. 

If  a  truss  rests  on  ma- 
sonry walls,  three  meth- 
ods of  making  the  details 
atjL0are  in  common  use. 
These  are  shown  in  Figs. 
55, 56,  and  57.  The  de- 
tail shown  in  Fig.  55  is 
the  most  commonly  used ; 
but  its  use  is  not  advised 
unless  a  sufficient  number  of  rivets  are  placed  in  the  members  to  take 
up  both  the  direct  stress  and  that  due  to  the  fact  that  the  point  of 
application  of  the  reaction  does  not  coincide  with  the  intersection 
of  the  center  lines  of  the  chord  members. 


Fig.  52.    Slotted-Hole  Expansion  Bearing. 


Fig.  53.    Roller  Expansion  Bearing. 


157 


ROOF  TRUSSES 


Fig.  56. 


Fig.  57. 
Details  of  Ends  of  Roof  Trusses. 


In  case  the  bearing  shown 
in  Fig.  55  is  used,  the  number  of 
rivets  in  L0  Lv  may  be  calcu- 
lated from  the  equation : 

n2    -R     -6Re 
P 

in  which, 

n  =  Number  of  rivets  required; 
v  =  Allowable  stress  on  one  rivet ; 
R  =  Vertical  reaction; 
p  =  Rivet  spacing,  in  inches; 
e  =  Distance  as  shown  in  Fig.  55. 

If  the  number  of  rivets  in  L0  C7X  is  desired,  it  may  be  calculated 
from  the  equation: 

P 

in  which  S  is  the  stress  in  L0  Uv  e  the  distance  shown  in  Fig.  55,  and 
the  remaining  notation  as  above. 

If  the  point  of  application  of  the  reaction  coincides  with  the 
intersection  of  the  center  lines  of  the  top  and  bottom  chords,  the 
number  of  rivets  required  to  withstand  the  direct  stress,  which  is  the 
only  stress  would  be  equal  to  the  stress  in  that  member  divided  by 
the  allowable  stress  in  one  rivet. 


158 


ROOF  TRUSSES 


37 


In  order  to  illustrate  the  use  of  the  above  equation,  and  to  bring 
out  the  fact  that  more  rivets  are  required  when  the  point  of  applica- 
tion of  the  reaction  does  not  coincide  with  the  intersection  of  the  upper 
and  lower  chords  than  when  it  does  coincide,  an  example  will  be 
solved.  The  stresses,  the  thickness  of  the  connection  plate,  and  the 
distance  of  the  point  of  application  of  the  reaction  from  the  inter- 
section of  the  chord,  are  as  shown  in  Fig.  58. 

It  will  be  assumed  that  the  chords  consist  of  two  angles  each; 
and  since  this  is  the  case,  the  allowable  unit-stress  in  one  rivet  will  be 


Fig. 


Data  for  Example  on  Page  37. 


Fig. 


Eave  Detail  for  Fig.  57. 


3  750  pounds,  the  value  of  a  f-inch  rivet  in  bearing  in  a  f-inch  plate 
when  the  allowable  unit  bearing  stress  is  20  000  pounds  per  square 
inch.  If  the  point  of  application  of  the  reaction  coincides  with  the 
intersection  of  the  two  chords,  the  number  of  rivets  required  will  be: 
45000 


For  L0  Ul 


For  L0  L, 


3750 


12.00  rivets. 


o  7oU 


=  10.67  rivets. 


Since  the  point  of  application  of  the  reaction  does  not  coincide 
with  the  intersection  of  the  chord,  the  number  of  rivets  required  in 


L0D>: 


3  750  w2  -  45  000  n 


6  X  45  OOP  X  4 . 44 
3 


the  spacing  being  3  inches;  dividing  by  3  750,  we  have: 
n2-  12n  =  106.56. 


159 


38  ROOF  TRUSSES 

Completing  the  square  and  solving  for  n,  there  is  obtained: 


n  =  6  +  V  142 . 56  =  17 . 9,  say  18  rivets. 
The  number  of  rivets  required  in  L0  Ll  is : 


3  750  n2  -  20  000  n  = 


X  20  OOP  X  10 
3 


and  dividing  by  3  750  and  completing  the  square,  there  results : 
n  =  2.67    +  Vll3.75=  13.32,  say  14  rivets. 

Inspection  of  the  above  results  shows  that  when  the  point  of 
application  of  the  reaction  is  placed  10  inches  from  the  intersection  of 
the  chords,  it  requires  6  more  rivets  in  the  upper  chord  and  3  more 
rivets  in  the  lower  chord  than  would  be  required  if  the  point  of  appli- 
cation of  the  reaction  coincided  with  the  intersection  of  the  chords. 


160 


ROOF  TRUSSES  39 

The  detail  just  discussed  is  a  very  convenient  one,  and  is  very 
commonly  used;  but  in  most  cases  no  allowance  is  made  for  the 
additional  rivets  required  because  of  the  fact  that  the  reaction  does  not 
coincide  with  the  intersection  of  the  chord  members.  The  student 
should  always  compute  the  rivets  by  the  formulae  given  above,  since 
it  is  very  evident  that  neglect  to  do  so  causes  the  joint  to  be  exceed- 
ingly weak,  in  some  cases  as  much  as  50  per  cent,  as  is  shown  in  the 
case  of  L0  L^  in  the  above  problem. 

Fig.  56  is  excellent,  but  the  length  of  the  bearing  plate,  which 
should  be  as  long  as  the  connection  plate,  is  liable  to  become  greater 
than  the  width  of  the  wall.  In  such  cases  the  detail  shown  in  Fig. 
57  is  to  be  used.  The  objection  raised  to  these  details  is  that  the  end 
connection  plate  prevents  the  placing  of  a  purlin  near  the  end  of  the 
roof  truss.  In  case  sheathing  is  used,  this  objection  does  not  hold 
good,  since  the  overhanging  sheathing  will  reach  to  the  end  of  the 
truss  and  form  a  good  eave  detail,  as  shown  in  Fig.  59. 

When  the  roof  truss  rests  on  steel  columns  which  are  composed 
of  latticed  angles,  the  connections  may  be  made  as  shown  in  Figs. 
60  and  61.  Fig.  60  is  preferable,  because  it  gives  a  more  rigid  con- 
nection than  is  given  by  Fig.  61.  If  the  columns  consist  of  two  panels 
placed  close  together,  back  to  back,  the  same  details  may  be  used.  If 
the  column  consists  of  one  I-beam  or  of  two  channels  placed  back  to 
back  at  some  distance  apart,  then  details  shown  in  Figs.  62  and  63 
may  be  used. 

Where  one  member  is  joined  to  another  and  makes  an  angle  or  is 
perpendicular  to  it,  then  details  as  shown  in  Figs.  64  and  65  may  be 
used.  It  is  not  good  practice  to  cut  the  angles  as  shown  at  b  in  Fig. 
65;  a  is  a  better  detail.  No  joints  should  have  less  than  two  rivets. 

In  places  where  three  members  meet,  and  two  make  the  same 
angle  with  one  of  the  others,  the  details  should  be  made  as  shown  in 
Fig.  66.  The  leg  of  the  angle  which  is  not  joined  to  the  plate  should 
always  be  upward.  This  prevents  the  dust  and  dirt  from  becoming 
mixed  with  the  moisture  and  running  or  jarring  down  into  joints  at 
the  lower  ends  of  the  members. 

At  L:  and  L3,  square  plates  (see  at  left,  Fig.  67)  should  be  used 
where  possible.  If  the  stresses  are  such  that  more  rivets  are  required 
in  one  member  than  in  the  other,  then  the  plate  should  be  cut  as 
shown  at  right  in  Fig.  67. 


161 


40 


ROOF  TRUSSES 


At  L2  the  splice  occurs,  since  Fink  trusses  are  usually  shipped 
in  two  parts.  In  addition  to  the  vertical  connection  plate,  which 
also  acts  as  a  splice  plate,  the  bottom  plate  is  used  (see  Fig.  68). 
Rivets  shown  in  black  indicate  that  the  holes  are  left  open,  the  pieces 
in  which  they  occur  are  shipped  separately,  and  then  are  riveted 
together  at  the  place  where  the  truss  is  put  up. 

In  some  cases  where  the  member  L2  L5  is  long  enough  to  sag 


a  b 

Fig.  65. 
Details  of  Roof  Truss  Connections.    See  also  Figs.  67  and  68. 

considerably,  or  where  it  is  desired  to  connect  a  load  (such  as  a  hand 
hoist)  at  its  center,  a  vertical  Ut  M  is  run  from  U4  and  connected  to 
the  lower  chord.  No  stress  is  caused  in  this  member  by  any  load 
except  the  load  at  M,  in  which  case  the  stress  is  equal  to  that  load. 
If  a  load  is  at  M,  it  will  cause  stresses  in  other  members  of  the  truss, 
the  stresses  in  the  truss  being  the  same  as  if  the  dead  panel  load  at 
Ut  were  increased  by  an  amount  equal  to  the  load  at  M. 


162 


ROOF  TRUSSES 


41 


Fig.  67. 


The  general  details  of  a  Fink  truss  are  shown  in  Plate  I  (p.  43) , 

Plate  II  (p.  60),  and  Plate  III  (p.  61). 

In  case  the  building  is  devoted  to  some  purpose  wherein  no 

smoke  or  noxious  gases  are  produced,  some  form  of  patent  ventilator 

may  be  used.     One  very 

excellent  make  is  shown 

in    Fig.    69— called    the 

Star     ventilator     (Mer- 

chant  &   Co.,  Philadel- 

phia,  Pa.).     These  ven- 
tilators are  made  from  2 

to  60  inches  in  diameter 

at     the    lower    portion, 

where    they    fit    to    the 

ridge  of  the  roof.     Fig. 

70  shows  one  of  them  in 

position  on  a  roof.     The 

number  and  size  of  these 

ventilators     depend     of 

course  upon  the  number 

of  times  per  hour  it  is   desirable  to  change    the  air  in  the  shop. 
In  case  the  shop  is  for  such  purposes  that  smoke,  gases,  or  noxious 

fumes  of  any  kind  are  produced,  it  is  desirable  to  have  some  channel 

for  ventilation 
which  is  consider- 
ably larger  than 
those  given  by  the 
patent  ventilators. 
In  such  cases  the 
ventilation  is  usu- 
ally obtained  by 
a  small  house- 
shaped  construc- 
tion called  a  lantern,  monitor,  or  ventilator  (see  Fig.  71).  The  sides 

of  these  ventilators  may  be  fitted  with  louvres  or  windows,  or  left 

open.     Louvres  may  be  made  either  of  wood  or  of  corrugated  or 

plain  bars.     For  details  of  monitors  and  louvres,  see  Figs.  124,  125, 

and  126. 


Fig.  68. 


Details  of  Roof  Truss  Connections. 
See  also  Figs.  64,  65,  and  66. 


Fig.  69.    Details  of  "Star"  Ventilators. 


163 


42 


ROOF  TRUSSES 


a       a       o       a 


ID    Dlfflfflfflffl 


Fig.  70.  "Star"  Ventilators  on  a  Roof, 


Fig.  71.    Detail  of  a  Monitor  Ventilator. 


Fig.  72.    Detail  of  Window  in  Saw-Tooth 
Roof. 


In  order  to  admit  sufficient 
light  into  the  building,  part  of  the 
roof  of  buildings  over  80  feet 
•wide  must  be  made  of  glass,  since 
the  amount  of  light  admitted  from  the  sides  of  the  building  is 
not  sufficient  to  light  up  those  parts  of  the  shop  near  the  center 
of  the  trusses.  In  some  cases  the  saw-toothed  truss  is  used,  in 
which  case  the  entire  surface  of  the  short  rafter  is  covered  with  glass. 
In  case  the  ordinary  triangular  roof  truss  is  used,  a  portion  of  the 
roof  covering  must  be  made  of  glass,  so  put  on  as  to  prevent  leakage 
and  also  to  prevent  the  moisture  which  forms  on  the  under  side  of 
the  glass  from  dropping  in  the  shop.  Fig.  72  shows  the  glass  in 
place  on  a  saw-toothed  roof;  and  Figs.  73  and  74  give  the  details  of 
several  methods  of  securing  glass  on  the  roof  so  that  no  leakage  or 
condensation  will  get  onto  the  shop  floor.  The  glass  area  should  be 
from  TY  to  £  of  the  floor  area. 

13.   Specifications  for  Roof  Trusses  and  Steel  Buildings.    In  case 
of  an  important  structure,  special  specifications  are  written,  embody- 


164 


.H  '.£•.£  II  -0->9  J'.tt'.t  HI 

J3/WO-]  buoojg  pJOqQ  jaddfl 


165 


44 


ROOF  TRUSSES 


Fig.  73.    ' '  Paradigm ' '  Method  of  Glazing. 


ing  certain  fea- 
tures which  the 
experience  of  the 
engineer  in  charge 
indicates  as  neces- 
sary. For  ordi- 
nary structures, 
however,  several 
very  satisfactory 
specifications  are 
on  the  market. 
These  consist  of 
from  15  to  20 
pages,  bound  in 
paper,  and  may 
be  had  for  twenty- 
five  cents  a  copy. 
Two  very  satis- 
factory specifica- 
tions are  those  of 
Charles  Evan 
Fowlerand  Milo  S. 
Ketchum.  Either 


may  be  had  by  addressing  the  Engineering  News  Publishing  Company, 
New  York  City.  Fowler's  specifications,  in  addition  to  giving  speci- 
fications for  load  stresses  and  workmanship,  give  much  valuable  in- 
formation regarding  the  stresses 
in  different  kinds  of  trusses,  be- 
sides various  details  showing  the 
use  of  corrugated  steel. 

An  extended  set  of  specifica- 
tions is  not  required  for  the  de-  ^•^^P^Skyliqht  Bar 
sign  of  ordinary  roof  trusses.    In  . 
addition  to  the  information  re- 
garding the  weight  of  trusses,  the  weight  of  roof  covering,  the  snow 
load,  and  the  wind  load,  the  use  of  Table  VIII  will  be  found  to  be  all 
that  is  necessary  in  order  to  design  cross-sections  of  the  various 
members,  once  the  stresses  are  determined. 


166 


ROOF  TRUSSES    .  45 

TABLE  VIII 
Allowable  Unit-Stresses,  Medium  Steel 

For  Shear 10  000  pounds  per  square  inch. 

For  Bearing 20  000       "  "        "          " 

For  Tension 15  000       "  "         "          " 

For  Bearing  of  Steel  on  Masonry 250  to  400       "'  "        "          " 

For  Compression P  =  24  000  -  110  - . 

In  case  the  stresses  are  those  due  to  crane  loads,  the  unit-stresses  in 
tension  and  compression  indicated  in  Table  VIII  should  be  reduced  J  and  £ 
respectively.  Members  of  the  lateral  bracing  and  their  connections  may  be 
allowed  an  increase  of  25  per  cent  over  the  unit-stresses  there  indicated. 

[n  the  equation  above  given  "For  Compression,"  /  is  the  length  of 
the  member  in  inches,  and  r  the  least  radius  of  gyration.     The  ratio 

of  -  should  never  be  greater  than  120. 

The  gauge  line  or  gauge  is  the  line  on  the  flange  of  a  shape,  on 
which  the  rivets  are  placed.  In  angles  and  channels  it  is  located  by 


Gage 


Double  Gaqe 


Single  Gaqe 


Channel 


(PL 

I- Beam 


Fig.  75.    Gauges  for  Angles,  Channels,  and  I-Beams. 

giving  its  distance  from  the  back  of  the  shape;  in  the  case  of  I-beams 
the  distance  between  two  gauge  lines  on  opposite  sides  of  the  web  is 
indicated.  Some  angles  have  double  gauge  lines,  in  which  case  the 
rivets  are  placed  first  on  one  and  then  on  the  other;  this  is  called 
staggering.  Fig.  75  shows  gauge  lines  for  various  shapes. 

Rivets  f  inch  in  diameter  are  generally  used  in  legs  of  angles  3  to 
4  inches  long  or  greater.  For  the  gauge  lines  and  the  maximum  sizes 
of  rivets  to  be  used  in  angles,  see  Table  IX.  For  similar  data  for 
channels  and  I-beams,  see  Carnegie  Handbook,  pp.  177-185. 

It  is  often  desirable  to  express  the  length  in  feet  instead  of  inches, 
in  which  case  the  formula  becomes: 

P  =  24  000  -  1  320  — . 


167 


46 


ROOF  TRUSSES 


TABLE   IX 
Gauges  and  Maximum  Allowable  Rivets  for  Angles 


MAXT- 

MAXI- 

MAXI- 

OR    BOLT| 

OK  BOLT 

BOLT 

8 

4^ 

\ 

•1 

31 

2 

1 

2 

U 

1 

7 

4 

1 

3 

i| 

1 

1| 

1 

1 

6 

3, 

i 

I 

2| 

If 

1 

11 

i 

1 

5 

3 

I 

21 

If 

f 

11 

1 

1 

4 

2^ 

\ 

I 

21 

H 

1 

i 

A 

i 

L 

01 

J7j 

L 

0i 

01 

8 

3 

3 

6* 

2 

t 

21 

7 

21 

3 

5 

2 

11 

6 

21 

21 

*  When  thickness  is  i  inch  or  over. 

For  convenience  in  designing,  the  values  of  L  -^  r  should  be  plotted 
as  ordinates,  and  the  resulting  values  of  P  as  abscissae,  on  cross- 
section  paper,  and  the  curve  drawn  in.  Then  the  value  of 
P  for  any  given  value  of  L  -f-  r  may  be  taken  at  once  from 
the  diagram  without  the  labor  of  substituting  in  the  above 
formula. 

The  bearing  value  of  a  rivet  in  a  plate  of  given  thickness  is  equal 
to  the  thickness  of  the  plate,  times  the  diameter  of  the  rivet,  times  the 
allowable  unit  bearing  stress.  The  value  of  a  rivet  in  single  shear  is 
equal  to  the  area  of  the  cross-section  of  the  rivet,  times  the  allowable 
unit  shearing  stress.  The  bearing  values  of  rivets  of  different  diam- 
eter in  plates  of  different  thickness,  and  the  shearing  values  of 
rivets  of  different  diameter,  are  given  in  Table  X,  the  unit-stresses 
being  as  given  above. 


168 


ROOF  TRUSSES 


47 


TABLE  X 
Bearing  and  Shearing  Values  of  Rivets 


BEARING  IN  DIFFERENT  THICKNESSES  OF  PLATES 

DIAMETER 

SINGLE  SHEAR 

(at  20  000  Ibs.  per  sq.  in.) 

OF  RIVET 

(at  10  000  Ibs. 

(Inches) 

per  sq.  in.) 

iin. 

ft  ia. 

tin. 

is  in- 

iin. 

ftin. 

iin. 

14  to. 

i 

1960 

2500 

3130 

3750 

& 

2480 

2810 

3520 

4210 

4920 

1 

3  070 

3130 

3910 

4690 

5470 

H 

3  710 

3440 

4290 

5160 

6010 

6880 

I 

4  420 

3750 

4690 

5630 

6560 

7500 

8440 

H 

5180 

4070 

5080 

6090 

7110 

8120 

9150 

10160 

1 

6010 

4380 

5470 

6570 

7660 

8750 

9840 

10940 

12040 

DESIGN  OF  A  RIVETED  ROOF  TRUSS 

14.  Let  it  be  required  to  design  a  Fink  roof  truss  of  64  feet  span 
and  I  pitch,  the  distance  between  trusses  being  16  feet.  The  roof 
covering  is  taken  as  12  pounds  per  square  foot  of  roof  surface,  and  the 
total  snow  and  wind  load  will  be  taken  as  30  pounds  per  square  foot 
of  horizontal  projection.  The  weight  of  the  steel  in  the  roof  truss 
will  be  computed  from  Merriman's  formula  (see  Art.  4,  p.  6).  The 
total  weight  is  now  found  to  be : 

Weight  of  truss,  -|-  X  16  X  64  (  1  +  -^-)  =      5  580  pounds. 

Weight  of  roof  cover,  35.6  X  2  X  16  X  12  =    13  650  pounds. 
Weight  of  wind  and  snow  64  X  16  X  30  =    30  700  pounds. 

Total          49  930  pounds. 

Each  apex  load  is  therefore  49  930  -r-  8  =  6  240  pounds.  By 
multiplying  this  value  by  each  of  the  stresses  as  given  in  Fig.  25,  the 
stress  in  each  member  is  computed  as  follows: 

L0  17,  =  7.83  X  6  240  =  48  800  pounds 
L0  L!  =  7.00  X  6  240  =  43  700 
Uv  L!  =  0.89  X  6240  ='  5580 
Ul  U2  =  7 . 38  X  6  240  =  46  000 
Lj  U2  and  U2  L3  =  1 .00  X  6  240  =  6  240 
A  L2  =  6.00  X  6240  =  37450 
U2  L2  =  1.79  X  6240  =  11  150 
U,  U3  =  6.93  X  6  240  =  43  200 
L2~  L5  =  4.00  X  6  240  =  24  950 
L2  L3  =  2.00  X  6  240  =  12  475 
U3  L3  =  0.89  X  6240  =  5580 
L3  U4  =  3.00  X  6  240  =  18  725 
Ua  Ut  =  6.48  X  6  240  =  40  500 


169 


48 


ROOF  TRUSSES 


In  the  design  of  this  truss,  no  material  thinner  than  £-inch,  and  no 

angles  smaller  than  1\  by  2-inch,  will  be  allowed. 

Fig.  76  shows  an  outline  diagram  of  the  truss,  with  the  stresses 

placed  upon  it.     A  positive  sign  signifies  a  tensile  stress,  and  a  negative 

sign  signifies  a  compressive  stress.     The  length  of  the  top  chords  is 

1/322  +  162  =  35.6  feet;  and  the 
length  of  each  panel  is  \  of  this, 
or  8 . 9  feet.  The  horizontal  pro- 
jection of  one  panel  is  \  of  half 
the  span,  or  32  -=-  4  =  8  feet. 

Design  of  the  Purlins.  The 
distance  between  the  trusses  is 
16  feet,  and  the  distance  between 
the  purlins  is  8.9  feet;  therefore 
the  load  coming  on  one  purlin  is : 


Fig.  76.    Stresses  in  a  Fink  Truss. 


Roof  covering,  8.9  X  16  X  12  =  1  710  pounds 
Snow  and  wind,  8  X  16  X  30    =3  840        " 


Total       =  5  550  pounds 

This  should  be  resolved  in  two  components,  Fand  H,  perpendicular 
and  parallel  to  the  truss  chord.  These  are  determined  by  the  pro- 
portions of  similar  triangles,  as  follows : 

7:5550  =32:35.6 

V  =  4  990  pounds. 
H  :  5  550  =  16  :  35.6 

H  =  2  495  pounds. 

The  bending  moment  caused  by  V  is  3/T  =  (4  990  X  16)  -f-  8  = 
9  980  pound-feet.  The  bending  moment  caused  by  H  is  MH  = 
(2  495  X  16)  -5-  8  =  4  990  pound-feet.  The  stress  caused  by  T  is  = 

— j-  ;  and  the  stress  caused  by  H  is  — — ;  and  there  is  also  the  con- 
dition that  the  sum  of  these  two  stresses  shall  not  be  greater  than 
15000  pounds.  Since  the  above  formula' involves  the  moment  of 
inertia  and  half  the  depth  of  the  beam,  a  beam  must  be  chosen,  and 
its  moment  of  inertia  and  half-depth  substituted  in  the  above  equa- 
tion, and  the  equation  solved-  In  case  the  sum  of  the  stresses  is  in 
excess  of  15  000  pounds,  or  very  much  smaller,  a  re-computation  must 
be  made,  using  a  larger  or  a  smaller  beam. 


170 


ROOF  TRUSSES  49 

A  15-inch  42-pound  I-beam  will  be  assumed,  and  will  be  examined 
to  see  if  it  fulfils  the  necessary  conditions.  The  value  of  I  and  /'  are 

taken  from  the  Carnegie  Handbook,  p.  97.     The  value  of  c  is  —  = 

5  50 
1\   in   the   first   case,  and  ~--  =  2.75  in  the  second  case.     The 

quantity  5 .50  is  the  width  of  the  flange  of  the  I-beam.  Substituting 
in  the  above  formula,  there  results : 

99*0X12X7^  +  4990X12X2.75  _  ^  ^  poundg 
441.8  14.OZ 

The  above  I-beam  could  be  used;  but  in  case  the  sheathing  is  laid 
closely  and  nailed  tightly,  we  may  consider  it  acting  as  a  beam  of  a 
span  of  16  feet,  8.9  feet  deep,  and  of  a  thickness  equal  to  that  of  the 
sheathing,  which  in  this  case  will  be  assumed  as  1^  inches.  The 
sheathing  will  then  take  up  the  moment  caused  by  the  force  H;  and 
the  purlin  will  take  up  the  vertical  bending  moment  alone.  The 

stress  in  the   sheathing  due  to   the  force  H   is  ^-~.     Here  M  = 

1   ^  (R  Q  V  1 9"\3 
4  990  X  12;  c  =  8.9  X  12  -  2;  and  I  =  -    l        A      j  .    Therefore, 

„  =  4  990  X  12  X  8.9  X  12  X  12 

2  X  1.5  (8.9  X  12)3 
=  20.95  pounds  per  square  inch,  which  is  insignificant. 

The  vertical  bending  moment  taken  up  by  the  purlin  is  9  980  X  12  = 
119  760  pound-inches,  and  this  requires  a  section  modulus  of  119  760 
4-  15  000  =  7.98.  By  consulting  pages  101  and  102  of  the  Carnegie 
Handbook,  the  following  is  found  to  be  true: 

An  8-inch  11.25-pound  channel  is  just  too  small. 
A     7-inch  17.25-pound  channel  gives  the  nearest  section  modulus. 
An  8-inch  13.75-pound  channel  would  be  lighter  and  stiffer. 
A     9-inch  13.25-pound  channel  would  be  still  lighter  and  stiffer;  and 
since  it  weighs  less  than  any  of  the  others,  it  will  be  more  economical'. 

A  9-inch  13.25-pound  channel  will  accordingly  be  used  for  the 
purlins. 

On  account  of  one  half-panel  load  coming  on  the  purlin  at  the 
ends  and  ridge  of  the  truss,  these  purlins  must  theoretically  be  only 
one-half  as  strong  as  the  other;  but,  on  account  of  the  fact  that  all 
purlins  must  be  of  the  same  height,  these  purlins  are  made  of  the 
lightest  weight  channel  of  the  same  height  as  the  others.  In  this 


m 


50  ROOF  TRUSSES 

case  it  happens  that  the  lightest  weight  9-inch  channel  is  required  for 
the  intermediate  purlins  as  well  as  for  the  end  ones.  To  illustrate 
the  above,  suppose  that  the  purlins  were  required  to  be  10-inch  25- 
pound  channels,  then  the  end  purlins  would  be  made  of  10-inch  15- 
pound  channels. 

In  case  sheathing  is  not  used,  then  some  other  method  must  be 
employed  to  take  up  the  bending  moment  due  to  the  force  H.  The 
usual  method  of  doing  this  is  to  bore  holes  in  the  center  of  the  purlins 
at  the  middle  point  of  their  span,  and  to  connect  them  with  rods 
which  run  from  one  eave  up  over  the  ridge  and  down  to  the  other  eave 
(see  Fig.  22). 

Design  of  Tension  Members.  For  Member  L0  L^.  The  re- 
quired net  area  is  43  700  H-  15  000  =  2.92  square  inches.  By  con- 
sulting the  Carnegie  Handbook,  p.  118,  it  is  seen  that  two  3  by  3 
by  TVinch  angles  give  a  gross  area  of  1.78  X  2  =  3.56  square 
inches.  From  this  must  be  subtracted  the  rivet-hole  made  by  a 
f -inch  rivet.  Since  all  rivet-holes  are  punched  £  inch  larger  in  diam  > 
ter  than  the  rivet,  the  amount  to  be  substracted  from  the  above 
gross  area  is  r5T  X  (f  +  i)  X  2  =  0.54,  there  being  two  rivet-holes 
taken  out  of  the  section.  This  gives  a  total  net  area  of  3 . 56  —  0 . 54 
=  3.02  square  inches.  As  this  is  but  slightly  larger  than  the  re- 
quired net  area,  these  angles  will  be  used  for  this  member.  Since 
the  stress  in  this  member  is  the  greatest  stress  in  the  bottom  chord, 
and  since  the  bottom  chord  is  made  of  the  same  section  up  to  the 
splice  at  L2,  on  account  of  economical  construction,  it  being  cheaper 
to  run  the  same  sized  angle  throughout  than  it  would  be  to  change 
the  size  of  each  panel  and  make  a  splice  at  each  panel  point,  the  size 
of  angle  as  determined  above  will  be  used  for  the  first  two  panels  of 
the  bottom  chord  at  each  end. 

For  Member  L2  L5:  The  required  net  area  is  24  950  -f-  15  000 
=  1 .67  square  inches.  From  Carnegie  Handbook,  p.  115,  two  angles 
2^  by  2  by  J-indh  give  a  gross  area  of  2  X  1 .06  =  2 . 12  square  inches; 
and  taking  out  two  f-inch  rivets,  the  net  area  is  2 . 12  —  |  (f  +  £)  X  2 
=  1 .74  square  inches.  This  coincides  very  closely  with  the  required 
area,  and  this  angle  will  be  used.  Even  if  this  angle  should  have 
been  in  excess  of  the  required  area,  it  would  still  be  necessary  to 
use  it,  since  it  is  the  smallest  angle  and  of  the  least  thickness 
allowed . 


172 


ROOF  TRUSSES  51 

For  Member  L3  U4:  The  required  net  area  is  18  725  -=-  15  000  = 
1 . 25  square  inches.  Two  angles  2  J  by  2  by  J-inch  give  a  gross  area 
of  2. 12  square  inches,  and  a  net  area  of  1 .74  square  inches,  as  above 
computed.  Although  they  give  an  area  considerably  larger  than  that 
required,  nevertheless  they  must  be  used,  since  they  are  the  smallest 
allowed. 

For  Members  L^  U2  and  U2  L3 :  The  required  net  area  is  6  240  'T- 
IS 000  =  0.42  square  inch.  One  angle  2^  by  2  by  J-inch  gives  a 
gross  area  of  1 .06  square  inches.  The  amount  to  deduct  from  this 
is  |  X  (|  +  i)  =  0.19  square  inch,  one  f-inch  rivet-hole  being  taken 
from  the  section.  This  gives  a  net  area  of  1 .06  —  0.19  =  0.87 
square  inch,  which  shows  this  angle  to  be  sufficient. 

Since  the  member  UtM  has  no  other  use  than  to  prevent  the 
bottom  chord  from  sagging,  it  will  be  made  of  the  lightest  angle 
allowed.  It  will  therefore  be  made  of  one  angle  2^  by  2  by  J-inch. 

The  member  L2  L3  is  made  of  the  same  section  as  the  member 
L3  Uv  since  this  is  more  economical  than  to  change  the  section  and  to 
make  a  splice  at  L3.  It  will  be  made  of  two  angles  2^  by  2  by  j-inch. 

Design  of  the  Compression  Members.  The  general  method  of 
procedure  in  the  design  of  compression  members  is,  first,  to  assume  a 
cross-section,  and  then  to  determine  the  unit  compressive  stress 
allowable  by  inserting  the  length  of  the  member  and  the  radius  of 
gyration  of  the  assumed  section  in  the  formula  given  for  the  unit 
allowable  compressive  stress;  then  divide  the  stress  in  the  member 
by  the  unit  allowable  compressive  stress  determined  as  above.  This 
will  give  the  required  area.  If  this  required  area  is  equal  to,  or  slightly 
less  than,  the  area  of  the  cross-section  assumed,  the  section  assumed 
will  be  the  correct  one.  If  the  required  area  as  computed  above  is 
greater  than  the  area  of  the  section,  then  a  larger  section  must  be 
assumed  and  the  operation  repeated.  Usually  only  two  operations 
are  required  in  order  to  obtain  a  section  whose  area  is  correct.  It 
should  be  noted  that  the  area  of  the  rivet-holes  is  not  deducted  from 
the  section  in  compression  members,  since  the  rivet  fills  up  the  rivet- 
hole  and  makes  a  section  as  strong  in  compression  as  it  was  in  the 
first  place.  Care  should  be  taken  to  assume  a  section  whose  radius 
of  gyration  is  equal  to  or  greater  than  the  length  of  the  member 
divided  by  120.  This  is  due  to  the  fact  that  I  -z- r  should  not  be 
greater  than  120.  Compression  members  of  roof  trusses  for  the  usual 


173 


52  ROOF  TRUSSES 

spans  are  made  of  two  angles  placed  back  to  back.  The  radius  of 
gyration  of  such  a  section  is  equal  to  the  radius  of  gyration  of  one 
angle,  if  it  is  referred  to  an  axis  perpendicular  to  the  legs  which  are 
placed  together.  If  it  is  referred  to  an  axis  through  the  center  of  the 
section  and  parallel  to  the  legs  which  are  placed  together,  it  is  equal 
to  some  value  other  than  the  radius  of  gyration  of  one  angle.  The 
radii  of  gyration  for  pairs  of  angles  placed  either  directly  back  to  back 
or  a  small  distance  apart,  are  given  on  pages  144  to  146  of  the  Car- 
negie Handbook  and  in  Table  XI,  and  should  be  used  in"the  design. 
The  value  of  the  radius  of  gyration  for  sizes  of  angles  other  than 
those  given,  may  be  obtained  by  interpolation. 

For  example,  let  it  be  required  to  determine  the  radius  of  gyra- 
tion of  two  5  by  3^  by  ^-inch  angles  placed  \  inch  apart  and  back  to 
back,  the  5-inch  legs  being  horizontal  (see  p.  146,  Carnegie  Hand- 
book). Since  this  value  is  not  given  in  the  tables,  it  must  be  inter- 
polated from  the  values  given  for  r2  for  the  above  sized  angle,  which 
are  T5C  inch  and  f  inch  thick.  The  difference  between  the  two 
thicknesses  given  is  •§  —  -^  =  &  inch.  The  difference  between 
the  two  values  given  for  the  radius  of  gyration  is  2 . 55  —  2 . 44  =  0.11. 
This  gives  a  difference  of  .11  -r-  9  =  0.0122  for  each  ^  inch  differ- 
ence in  thickness  in  the  angle.  The  difference  between  the  thickest 
angle  and  the  angle  under  consideration  is  f  —  i  =  f,  or  T\. 
Therefore  the  amount  to  be  subtracted  from  the  radius  of  gyration  of 
the  thickest  angle  is  6  X  0.0122  =  0.0732; and  the  radius  of  gyra- 
tion for  two  angles  placed  back  to  back  as  above  stated  is  2 . 55  —  0 . 07 
=  2 .48.  In  case  one  angle  is  used  for  a  member  in  compression,  the 
least  rectangular  radius  of  gyration  must  be  used;  and  if  two  angles 
are  employed,  placed  back  to  back,  care  should  be  exercised  to  use 
the  least  radius  of  gyration;  and  if  the  angles  have  unequal  legs,  those 
legs  should  be  placed  back  to  back,  which  will  make  the  rectangular 
radii  of  gyration  as  nearly  equal  as  possible.  The  values  of  the 
radii  of  gyration  will  indicate  whether  the  short  legs  or  the  long  legs 
should  be  placed  together.  The  tables  given  in  the  Carnegie  Hand- 
book give  the  radii  of  gyration  for  angles  spaced  at  distances  %  inch 
and  f  inch  apart;  but  since  the  connection  plates  of  roof  trusses  are 
usually  j  inch  or  f  inch  thick,  the  values  of  the  radii  of  gyration 
should  be  given  for  angles  spaced  f  inch  and  f  inch  apart.  Such 
values  are  given  in  Table  XI. 


174 


ROOF  TRUSSES 


53 


TABLE  XI 
Radii  of  Gyration  of  Angles  Placed  Back  to  Back 


EQUAL  LEGS 


UNEQUAL  LEOS 


. 

SIZE  (Inch.6s) 

SIZE  (Inches) 

1 

* 

1 

* 

2     X  2     X  A 

0.93 

0.98 

21  X  2     X  A 

0.88 

0.92 

1.19 

.24 

2     X  2     X  T7e 

0.98 

1.03 

21  X  2     XI 

0.94 

0.99 

1.25 

.30 

21  X  21  X  i 

1.14 

1.19 

3     X  21  X  i 

.09 

.13 

1.40 

.45 

21  X  2$  X  1 

.19 

1.24 

3     X  21  X  T9ff 

.15 

.20 

1.46 

.51 

3     X  3     X  i 

.34 

1.39 

31  X  21  X  i 

.04 

.09 

1.67 

.72 

3     X  3     X  f 

.41 

1.46 

3*  X  2*  X  H 

.13 

.18 

1.75 

.80 

31  X  31  X  f 

.56 

1.61 

3|  X  3     X  & 

.30 

.35 

1.61 

1.66 

31  X  31  X  H 

.65 

1.70 

31  X  3     X  it 

.40 

.45 

1.71 

1.76 

4     X  4    X  TB<T 

.76 

1.80 

4     X  3     X  A 

.25 

.30 

1.88 

1.93 

4     X  4     X  ft 

1.85 

1.89 

4     X  3     X  H 

.35 

.40 

1.97 

2.02 

6     X  6     X  T7g 

2.58 

2.63 

5     X  3     X  TBe 

.17 

.22 

2.42 

2.47 

6X6X| 

2.66 

2.70 

5     X  3     X  if 

.27 

.32 

2.52 

2.57 

5     X  3^  X  1 

.42 

.46 

2.36 

2.41 

5     X  31  X  J 

.51 

.56 

2.45 

2.50 

6     X  31  X  f 

.34 

.39 

2.90 

2.95 

6     X  31  X  i 

.44 

.49 

3.00 

3.05 

6X4X| 

.58 

.62 

2.83 

2.87 

6     X  4     X  J 

.67 

.71 

2.92 

2.97 

r0  =  In  all  cases,  the  radius  of  gyration  of  one  angle  referred  to  neutral  axis  paral- 
lel to  the  horizontal  leg  as  shown  above. 

For  Member  L0Ut:  Two  angles  3$  by  3  by  ^  -inch,  long 
legs  spaced  back  to  back,  and  \  inch  apart,  will  be  assumed.  The 
least  radius  of  gyration  is  1  .  10,  and  the  length  is  8  .  9  feet.  The  area 
of  this  section  is  2  X  1  .  93  =  3  .  86  square  inches.  The  unit  allowable 
compressive  stress  is: 

P  =  24  000  -  n° 


The  required  area  is  48  800  -^13  400  =  3.65  square  inches.  Since 
the  angles  given  are  of  somewhat  larger  area  than  that  required,  it 
might  be  well  to  examine  the  next  smallest  angle. 

Two   angles  3*  by  2$  by  &-inch,  with  a  radius  of  gyration 


175 


54  ROOF  TRUSSES 

1.11  and  a  total  area  of  3.56  square  inches,  will  be  assumed.  The 
unit  allowable  compressive  stress  is: 

P  =  24  000  --1°X11121X8-9=  13  510  pounds. 

The  required  area  is  48  800  -f-  13  510  =  3.61  square  inches.  Since 
the  required  area  is  greater  than  the  given  area,  it  shows  that  these 
angles  are  too  small.  Two  angles  3^  by  3  by  T58-inch  will  there- 
fore be  used  for  this  member,  and  also  for  all  the  members  of  the  top 
chord,  since  it  is  more  economical  to  run  the  same  size  throughout 
than  to  change  the  section  and  make  splices  at  all  the  upper  chord 
panel  points. 

For  Member  U2  L2:  The  length  of  this  member  is  easily  com- 
puted from  similar  triangles,  and  is  found  to  be  8.9  feet.  Two  angles 
1\  by  2  by  T56-inch,  with  the  long  legs  back  to  back,  give  a  total  area 
of  1.62  square  inches  and  a  radius  of  gyration  of  0.78.  The  unit- 
stress  is  computed  and  found  to  be  8  950  pounds.  The  required  area 
is  1 1  150  -j-  8  950  =  1 . 25  square  inches.  These  two  angles  would 
be  used,  but  the  least  allowable  radius  of  gyration  is  8.9  X  12  -r-  120 
=  0 . 89.  This  is  seen  to  be  considerably  greater  than  the  radius  of 
gyration  given  above,  and  therefore  these  angles  cannot  be  used, 
according  to  Specifications.  By  consulting  the  tables,  it  is  seen  that 
two  angles  3  by  2^  by  J-inch  are  the  smallest  angles  that  will  give  a 
radius  of  gyration  nearest  to  the  required  amount  (0.89)  and  still 
be  standard  size  angles.  Angles  marked  with  a  star  in  the  tables 
are  special  angles,  and  can  be  procured  only  at  a  cost  greatly  in  excess 
of  the  others,  and  then  only  with  great  delay  in  delivering  except 
when  large  quantities  are  ordered.  It  may  be'  said  that  special 
angles  should  never  be  used. 

For  Members  Ut  Lt  and  U3  L3:  The  length  of  these  members  is 
4.45  feet.  The  radius  of  gyration  must  therefore  not  be  less  than 
4.45  X  12  H-  120  =  0.45.  One  angle  1\  by  2  by  J-mch,  with  an 
area  of  1 .06  square  inches  and  a  least  rectangular  radius  of  gyration 
of  0 . 59,  will  be  assumed.  The'allowable  unit  compressive  stress  is : 

110  x  12  x8^9- 
P  =  24  000 — .r-eq =  14  05°  pounds. 

The  required  area  is  5  580  •*•  14050  =  0.40  square  inch.  The 
angle  chosen  gives  a  much  larger  area  than  that  required;  but  since 
it  is  the  smallest  one  allowed  by  the  Specifications,  it  must  be  used. 


176 


ROOF  TRUSSES  55 

Many  designers  do  not  place  a  limit  on  the  value  of  the  radius 
of  gyration,  but  simply  use  the  compressive  formula,  and  any  section 
whose  radius  of  gyration  will  bring  the  required  area  near  to  its  own 
area.  This  should  not  be  the  case,  since  the  formula  here  given  is  not 
applicable  when  the  value  of  I  -r-  ris  greater  than  120. 

Top  and  Bottom  Lateral  Bracing.  Since  the  stresses  in  the 
lateral  bracing  are  not  susceptible  of  a  well-defined  mathematical 
analysis,  it  cannot  be  rationally  designed.  Experience  indicates  that 
it  should  be  as  in  Article  7.  The  lower  chord  bracing  will  therefore 
consist  of  single  angles  3  by  2J  by  y^-inch;  and  the  upper  chord 
bracing,  of  3  by  3  by  T5^-inch  angles.  This  bracing  should  not  be 
placed  between  every  truss,  but  should  be  placed  as  indicated  on  the 
stress  sheet,  Plate  I.  If  one  f-inch  rivet  is  taken  out  of  the  section  of 
the  bottom  lateral  bracing,  it  will  give  a  net  area  of  1.62  —  0.27  = 
1 .35  square  inches;  this  could  withstand  a  stress  of  1 .35  X  15  000  X 
1 .25  =  27  000  pounds,  which  is  the  stress  the  bracing  is  assumed  to 
carry,  and  which  is  to  be  used  in  determining  the  number  of  rivets 
for  the  connection.  The  stress  in  the  top  lateral  bracing  may  be 
assumed  to  be  the  same. 

Determination  of  Number  of  Rivets  Required.  It  is  to  be  remem- 
bered that  f-inch  rivets  are  to  be  used  in  the  2^  and  2-inch  legs  of  the 
angles,  and  f-inch  rivets  in  all  larger  legs.  Field  rivets  are  to  have 
a  value  equal  to  §  of  a  shop  rivet.  Connection  plates  f  inch  thick 
are  to  be  used  in  all  cases,  except  where  the  number  of  rivets  required 
will  be  greater  than  10.  In  such  cases,  use  a  f-inch  connection  plate. 
The  correct  number  of  field  rivets  may  be  determined  by  multiplying 
the  required  number  of  shop  rivets  by  |. 

Whenever  two  angles  back  to  back  join  on  a  plate,  the  number 
of  rivets  is  governed  by  the  bearing  on  the  connection  plate;  and  when 
one  angle  is  joined  to  a  plate,  the  number  of  rivets  is  governed  by 
single  shear  if  the  rivet  is  f  inch  in  diameter,  and  by  single  shear  if  the 
rivet  is  f  inch  in  diameter  and  the  plate  is  over  \  inch  thick.  The 
bearing  and  shearing  value  of  the  rivets  are  taken  from  Table  X,  p.47. 

Lower  End  of  L0  U^.     Rivets  f-inch.     Plate  f-inch. 

48  800  -H  5  630  =  9  shop  rivets  required. 
Upper  End  of  U3  U4:     Rivets  f-inch.     Plate  f-inch. 

40  500  -=-  5  630  =  8  shop  or  10  field  rivets 
Upper  End  of  U4  L3:     Rivets  |-inch.     Plate  f-inch. 

18  725  -r  4  690  =  4  shop  or  6  field  rivets. 


177 


56  ROOF  TRUSSES 

Lower  End  of  L2  L3:     Rivets  f-inch.     Plate  J-inch. 

12  474  -H  3  130  =  4  shop  rivets. 
Each  End  of  U2L2:     Rivets  £  -inch.     Platen-inch. 

11  150  H-  3  130  =  4  shop  rivets. 
Each  End  of  Ij  U2  and  U2  L3:     Rivets  f-inch.     Plate  i-inoh. 

6  240  -H  3  070  =  2  shop  rivets. 
Each  End  of  Ul  L,  and  U3  L3:     Rivets  f-inch.     Plate  1-inch. 

5  580  -=-  3  070  =  2  shop  rivets. 

Where  U^  and  U^  join  the  top  chord,  two  rivets  will  be 
required  in  the  top  chord. 

Since  the  components  of  the  two  diagonals  meeting  at  £7,  are 
parallel  and  equal,  and  opposite  to  the  stress  in  U2  L2,  no  rivets  will 
be  required,  theoretically,  to  hold  the  plate  to  the  top  chord.  A 
sufficient  number,  however,  must  be  put  in  to  take  up  the  vertical 
reaction  of  the  purlin.  This  number  is  5  550  -r-  3  130  =  2  shop  rivets. 
In  practice  a  greater  number  are  usually  put  in  to  prevent  vibration 
and  to  fill  out  the  plate. 

At  L3  a  sufficient  number  of  rivets  must  be  placed  in  L2  f74  to  take 
up  the  difference  in  stress  between  L3  Ui  and  L2  Ly  The  number 
required  is  (18  725  -  12  475)  ^  3  130  =  3  shop  rivets. 

At  the  end  L0  of  the  member  L0  Lv  there  is  a  horizontal  stress 
of  43  700  pounds,  and  a  vertical  force  equal  to  the  reaction,  which  is 
49  930  -T-  2  =  24  965  pounds  (see  Fig.  76).  The  force  acting  on 
the  rivets  in  this  member  is  the  resultant  of  these  two  forces,  and  is: 

\/43  7002  +  24  9652  =  50  300  pounds. 

Since  the  rivets  are  f-inch  and  the  plates  f-inch,  the  number  of  rivets 
required  is  50  300  -r-  5  630  =  9  shop  rivets.  This  number  should  be 
placed  symmetrically  with  respect  to  the  intersection  of  the  two 
chords.  In  case  the  point  of  application  of  the  reaction  had  not 
coincided  with  the  intersection  of  the  chords,  the  number  of  rivets  must 
be  computed  according  to  the  formula  on  page  36. 

For  the  joint  at  Lv  a  sufficient  number  of  rivets  must  be  put  in, 
in  order  to  take  up  the  difference  in  stress  between  the  members 
L0  LI  and  Lx  L2.  The  number  required  is  (43  700  -  37  450)  -r-  3  750 
=  2  shop  rivets. 

The  purlins  have  a  horizontal  shear  at  each  end,  of  H  -±-2  = 
2  490  -T-  2  =  1  245  pounds.  This  requires  1  245  ^  4  420  -  1  shop 
rivet  or  1  field  rivet,  to  keep  them  from  sliding  down  on  the  top 
chord.  Clip  angles  5  by  3^  by  f-inch  will  be  used  as  shown  in  Plate  L 


178 


ROOF  TRUSSES 


57 


Fig.  77.  Detail  Showing  Clip  Angle 
Connection. 


These  help  in  the  erecting  of  the  purlins,  since  they  are  shop-riveted 
to  the  truss  and  therefore  hold  the  purlins  in  place  while  they  are 
being  field-riveted  to  the  truss  and  to  the  clip  angles  (see  Fig.  77). 

Rivets  in  Lateral  Bracing.  The  plates  of  the  lateral  bracing  should 
be  made  i  inch  thick.     The  3- 
inch  leg  of  the  angle  will  be 
placed  against  the  plate.     Riv- 
ets f  inch  in  diameter  can  then 
be  used,  and  the  strength  of  the     C»P  Angle 
joint  will  be  governed  by  bear- 
ing in   the  J-inch  plate.     The 
stress  for  which  the  rivets  are 
to  be  determined  is  given  on  p. 
55.     It  is  27  000  pounds.     The 
number  of  field  rivets  in  bearing 
in  J-inch  plate,  required  to  with- 
stand the  stress,  is  (27  000  •*•  4  420)  X  -|  =  9.     The  size  and  shape 
of  the  plate  can  be  determined  only  while  making  the  detailed  draw- 
ing (see  Plate  III,  p.  61). 

Design  of  the  Splice.     The  general  details  of  the  splice  will  be  as 
shown  in  Fig.  68.     The  plate  underneath  will  be  made  J  inch  thick, 

the  same  thickness  as  the  ver- 
tical connection  plate  at  this 
point.  Note  that  the  member  on 
the  left-hand  side  of  the  splice 
must  have  f-inch  shop  rivets,  and 
the  member  on  the  right-hand 
side  must  have  f-inch  field  rivets. 
The  total  number  of  rivets  on 
either  side  of  the  splice  must  be  sufficient  to  take  up  the  entire 
stress  of  the  member  through  which  they  are  driven.  If  eight  f-inch 
field  rivets  are  driven  through  the  horizontal  legs  and  the  bottom 
splice  plate,  and  five  f-inch  field  rivets  are  driven  through  the  ver- 
tical plate  and  legs  of  the  angles  (see  Fig.  78),  the  total  strength 
of  the  joint,  remembering  that  the  rivets  are  f-inch,  will  be: 

8  X  f  X  3  070  =  16  370  pounds. 
5  X  i  X  3  130  =  10  430  pounds. 

Total       26  800  pounds. 


6  Shop 


5  FTeld 


Fig.  78.    Detail  of  Lower  Chord  Splice. 


179 


58  ROOF  TRUSSES 

Note  that  the  rivets  through  the  bottom  splice  plates  are  governed 
by  single  shear;  and  those  through  the  vertical  plate,  by  bearing  in 
the  plate.  Since  16  370  pounds  is  the  value  of  the  rivets  through  the 
bottom  splice  plate,  this  amount  will  be  transmitted  to  the  other  side, 
where  it  must  be  taken  up  by  shop  rivets.  Bearing  in  the  plate 
governs  the  number  of  f-inch  shop  rivets  required.  This  number 
is  16  370  -5-  3  750  =  5.  Since  16  370  pounds  of  the  stress  in  the 
member  Ll  L2  is  taken  up  by  these  5  shop  rivets,  the  remainder, 
37  450  -  16  370  =  21  080  pounds,  must  be  taken  up  by  the  rivets 
through  the  vertical  connection  plate.  This  requires  21  080  -r-  3  750 
=  6  shop  rivets. 

Since  16  370  pounds  is  transmitted  from  one  side  of  the  splice 
to  the  other  by  means  of  the  bottom  splice  plate,  this  plate  should  be 
16370  -5-  15000  =  1.09  square  inches  in  net  section.  The  net 
width,  the  plate  being  |  inch  thick,  is  1.09  -j-  0.25  =  4.36  inches. 
If  two  f-inch  rivet-holes  are  taken  out  of  the  section,  the  entire  width 
of  the  plate  must  be  4.36  +  2  (f  +  $)  =  6. 11,  say  7  inches  wide. 
The  length  of  the  plate  must  be  sufficient  to  get  in  the  number  of 
rivets,  and  this  length  is  determined  in  detailing. 

Design  of  the  Masonry  Plate.     If  this  truss  rested  upon  a  masonry 
wall,  it  would  require  a  bearing  of  (49  930  -r-  2)  -=-  250  =  100  square 
inches.     The  width  of  the  plate  cannot  be 
'Anchor  bolt    less  than  twice  the  width  of  the  legs  of  the 
bottom  chord  angle,   nor  should  it  extend 
outside  the  legs  of  the  chord  angle  more  than 
3  inches  on  each  side.     The  masonry  plate 
will  be  assumed  as  12  inches  wide,  in  which 
Fig.  79.  slotted  Hole  for      case  it  must  be  100  -j- 12  =  8.34,  say  8i  inches 

Truss  of  Fig.  76. 

long.     The  thickness  should  be  J  inch. 

Temperature  Allowance.  Slotted  holes  must  be  put  in  one  end 
of  the  truss,  to  allow  for  a  variation  of  150  degrees  in  temperature. 
A  common  rule  is  to  allow  |-inch  expansion  for  every  ten  feet  of  span. 
The  total  allowance  for  expansion  is  64  X  i  =  say,  1  inch.  Since 
the  bolts  which  go  through  this  hole  are  f  inch  in  diameter,  the  hole 
must  be  long  enough  to  allow  for  £  the  expansion  on  each  side.  The 
width  of  the  hole  should  be  |  inch  greater  than  the  diameter  of  the 
bolt  (see  Fig.  79). 

Connections  to  the  Posts.     If  the  truss  rests  upon  posts  at  the  end, 


180 


ROOF  TRUSSES  59 

sufficient  rivets  must  be  driven  through  the  posts  and  the  end  con- 
nection plates  to  take  up  the  end  reaction,  which  (see  page  38)  is 
24  970  pounds.  Since  the  rivets  are  field  rivets,  this  will  require 
24  970  -r-  3  750  =  7.  This  number  is  to  be  used  in  case  the  posts  are 
built  in  masonry  walls.  In  case  the  truss  has  knee-braces  and  the 
walls  of  the  building  consist  of  steel  framework,  the  reaction  due  to 
the  wind  must  be  added  to  the  above. 

15.  The  Stress  Sheet.    This  should  also  be  somewhat  of  a 
general  drawing,  showing  the  details.  It  should  give  an  outline  sketch 
of  the  building,  showing  bays,  the  distances  between  trusses,  and  the 
bracing  in  the  plane  of  the  top  and  bottom  chords.     See  Plate  I, 
p.  43,    which  is  a  stress  sheet  of  the  truss  designed  in  Article  14. 
While  not  necessary,  it  is  very  convenient  to  have  the  required  number 
of  rivets  noted  upon  the  stress  sheet. 

16.  The  Detail  Drawing.    The  stress  sheet,  in  the  matter  of 
sizes,  gives  general  dimensions  only.     It  would  be  impossible  for  the 
shop  men  to  make  a  truss  from  the  stress  sheet. 

The  shop  or  detailed  drawings  must  be  prepared  by  the  drafts- 
man. These  drawings  must  show  the  exact  number  of  rivets,  and 
their  positions,  the  dimensions  of  every  plate,  member,  and  purlin. 
The  placing  of  the  dimensions  so  that  it  will  be  unnecessary  to  add 
or  subtract  in  order  to  get  another  desired  dimension,  is  quite  an  art, 
and  can  be  attained  only  through  experience  or  from  the  study  of 
correctly  detailed  work.  Plates  II  and  III  give  the  shop  drawings 
for  a  roof  truss  and  the  bracing.  These  are  made  according  to  the 
latest  and  best  practice,  and  a  thorough  study  of  them  will  be  a  help 
to  an  intelligent  design  of  the  trusses. 

All  members  and  plates  which  are  to  be  riveted  together  in  the 
field  should  be  given  a  mark.  This  mark  should  be  painted  on  the 
member  or  plate,  and  also  marked  on  the  Marking  or  Erection 
Diagram  (see  Plate  IV).  This  diagram  is  a  sketch,  with  the  pieces 
in  their  proper  position  and  the  correct  mark  placed  upon  them.  For 
example,  if  it  is  desired  to  rivet  into  place  the  first  panel  of  the  lower 
lateral  system,  the  men  look  on  the  marking  diagram  and  see  that 
plates  P17,  P18,  and  P/a,  and  the  laterals  BL1,BL2,  and  BL3  are 
required.  They  would  then  go  to  the  place  where  all  the  trusses  are 
piled  up,  and  pick  out  the  plates  and  members  with  these  marks  upon 
them.  They  would  then  rivet  P/7  at  L0,  Pls  or  P19  at  L2,  then  B  L 1, 


181 


182 


183 


X£J_ 


o: 


e 


0. 


X£J_ 


£ 


.O-.V9 


it  II 


ROOF  TRUSSES 


63 


then  BL3,  ?nd  finally  B  L  2,  all  of  which  are  shown  on  the  Marking 
or  Erection  Diagram. 

Care  should  be  taken  to  give  each  piece  that  is  different  from 
others  in  any  way  whatsoever,  a  different  mark.  For  instance,  the 
purlins  are  the  same  size,  and  differ  only  in  length  and  on  account  of 
the  fact  that  one  has  holes  in  the  bottom  flange  (see  Plate  III). 

Plate  IV  gives  the  roof  marking  and  erection  diagram  for  the 
roof  trusses  of  Plates  II  and  III.  Note  that  the  roof  truss  on 
Plates  II  and  III  is  not  the  same  as  that  of  which  Plate  I  is  a 
stress  sheet. 

17.  Estimate  of  Cost.  A  rough  estimate  of  the  cost  of  steel  in 
the  roof  may  be  obtained  by  multiplying  the  weight  of  the  purlins, 
in  pounds,  by  2^  cents;  then  adding  to  this  the  result  obtained  by 
multiplying  the  weight  of  all  the  steel  in  the  trusses  and  the  bracing 
by  3J  cents.  This  will  give  the  cost  of  the  steel  work  in  place  with 
two  coats  of  paint.  This  will  give  the  cost  closely  enough  for  an 
Engineer's  estimate;  but  should  a  Contractor  desire  to  bid,  a  detailed 
estimate  should  be  made  as  indicated  in  the  remainder  of  this  article. 

The  cost  of  the  roof  covering  may  be  approximately  determined 
according  to  the  prices  given  in  Article  5,  but  may  be  more  accurately 
obtained  by  asking  a  Contractor  for  a  figure  which  his  experience 
will  indicate  as  correct. 

Paint  of  various  kinds  may  be  bought  in  open  market.  Table 
XII  gives  some  of  the  kinds  used  in  painting  structural  steel,  to- 
gether with  the  amount  of  surface  one  gallon  will  cover. 

TABLE  XII 
Surface  Covered  per  Gallon  of  Paint* 


SQUAR 

E  FEET 

PAINT 

1  coat 

2  coats 

Iron  Oxide  (powdered)  
"           "     (ground  in  oil)  

600 
630 
630 

350 
375 
375 

500 

300 

Graphite                "       "     " 

360 

215 

Black  Asphalt                                        

515 

310 

875 

*Pencoyd  Handbook,  1898,  p.  293. 


185 


64 


ROOF  TRUSSES 


One  gallon  of  paint  will  give  two  tons  of  structural  steel  the  first 
coat,  or  2?r  tons  the  second  coat.  The  cost  of  one  coat  of  paint  in  the 
shop  is  45  cents,  and  two  coats  after  erection  $1.80  per  ton  of  struc- 
tural steel.* 

The  detailed  estimate  of  the  cost  of  steel  includes  several  items 
which  are  given  in  Table  XIII.  In  each  case  the  weight  of  the  steel 
on  which  the  work  is  done  must  be  multiplied  by  the  unit-cost,  and 
the  sum  total  of  all  the  costs  will  be  the  total  cost  of  the  entire  roof  or 
building.  Table  XIII  gives  the  various  operations  which  go  to  make 
up  the  cost,  and  also  the  unit-costs.  Note  that  the  costs  vary  con- 
siderably. This  table  is  given  as  a  rough  guide.  In  order  to  ana- 
lyze intelligently  the  cost  in  this  manner,  great  experience  or  access 
to  the  cost  records  of  some  structural  steel  company  is  necessary. 

TABLE  XIII 
Analysis  of  Cost  of  Roof  Trusses  and  Mill  Buildingsf 


OPERATION 

COST  PKR  TON 

Raw  Material 

$37.00  to  $40.00 

Work  done  at  Rolling  Mills  (mill  work) 

3.00 

7.00 

!  Columns 

14.00 

20.00 

Trusses 

12.00 

25.00 

Girders 

12.00 

25.00 

Work  done  in  Drafting  Room  \   „ 
}   Trusses  and  Buildings 

.30 
2.00 

1.00 
8.00 

Painting 

1.50 

3.00 

Shipping  (depends  upon  freight  rates) 
Erection 


5.00 


15.00 


It  is  not  to  be  supposed  that  all  of  the  operations  indicated  in 
Table  XIII  are  made  on  one  piece.  Usually  pieces  which  have  mill 
work  done  on  them  require  no  shop  work.  In  such  cases  a  saving 
of  freight  is  effected,  since  the  material  may  be  shipped  directly  from 
the  mill  to  the  place  of  erection. 

MILL  BUILDING 

18.  Definitions  and  Description.  A  mill  building  consists  of 
a  roof  supported  either  on  steel  columns,  on  steel  columns  built  in 


*Pencoyd  Handbook,  1898,  p.  293. 

•(•Compiled  from  Ketchum's  "  Steel  Mill  Buildings.' 


186 


ROOF  TRUSSES 


65 


masonry  walls,  or  on  masonry  walls  alone.  The  roof  may  consist  of 
any  of  the  forms  of  roof  trusses  that  have  previously  been  mentioned ; 
and  the  roof  covering,  which  may  rest  on  purlins,  or  on  rafters  and 
purlins,  may  consist  of  any  of  the  roof  coverings  mentioned  in  Article 
5.  In  case  the  roof  is  supported  on  steel  columns,  the  columns  are 
connected  at  their  tops  by  a  strut  called  the  eave-strut',  and  they  are 


Purlin 


/'"^ 

^?f 

tca»J_.  ^ 

^__^___^, 

~~~^-r-r  "^ 

I  \       / 

Lave  5^K" 

E 

^5^^ 

\ 

v 

/      N 

< 

iirtj 

- 

£ 
« 

; 

\4 

E 

I 

1 

0 

o 

j 

/ 

\ 

Girt' 

1 

5ide  Elevation 
Dotted  Lines  Indicate  Lateral  5rac»nq 


Tru55  Bent  ( Intermediate ) . 


,fV>>| 

„ 

S^ 

y>^ 

„ 

^\ 

\      / 

m 

\          / 

\  / 

\     / 

-A 

Column  - 
Column  - 

f 

"I 
0 

-X- 

/    \ 

/      \ 

Fig. 


Braced  End  Bent 
Physical  Analysis  of  a  Mill  Building. 


also  connected  at  certain  distances  throughout  their  height  by  hori- 
zontal members  called  girts.  The  building  may  or  may  not  have  a 
monitor  ventilator  on  top.  See  Fig.  80  for  general  form  of  mill 
buildings,  together  with  the  names  of  the  various  parts. 

The  eave-struts  and  the  girts  are  used  as  a  framework  on  which 
to  place  the  covering  for  the  walls  of  the  building.  This  covering 
may  be  of  wood,  of  wire  lath  and  plaster,  or  of  corrugated  steel. 
The  eave-strut  may  also  act  as  the  end  purlin. 

Since  the  majority  of  mill  buildings  have  their  roofs  and  sides 
covered  with  corrugated  steel,  the  remainder  of  this  text  will  be 
devoted  to  mill  buildings  with  this  kind  of  covering. 


187 


66 


ROOF  TRUSSES 


19.  Types  of  Buildings.  Mill  buildings  may  be  classified 
according  to  their  width  and  the  number  of  bays  which  they  have. 
A  building  may  consist  of  one  center  bay  (see  Fig.  81).  In  this  case 


^1W 


Glass 


Glass 


30  to  100  feet. 

Fig.  81. 


30  to  40  feet         30  to  60  feet 
Fig.  82. 


30  to  40  feet  30  to  60  feet  30  to  40  feet 


r. 
Glass 


North 


Glass 


Saw  Tooth 

Fig.  84. 


20  to40footspan5. 
Ketohum's  Modified  SawTooth 


Fig.  85. 


Cross-Sections  of  Mill  Buildings. 


the  span  may  vary  from  30  to  100  feet.  Usually  side  windows  give 
sufficient  light,  no  skylights  being  required  in  the  roofs  or  monitor  if 
the  span  is  less  than  80  feet. 

The  building  may  consist  of  one  center  bay  and  one  or  two  side 


188 


ROOF  TRUSSES  67 

bays,  as  shown  in  Figs.  82  and  83.  The  truss  of  the  center  bay  is 
usually  of  the  Fink  type,  and  in  most  cases  is  supplied  with  skylights 
and  lights  in  the  monitor.  The  side  trusses  for  the  most  part  consist 
of  that  type  in  which  the  chords  are  nearly  parallel.  The  center  bay 
is  generally  not  more  than  60  feet  in  span.  This  is  due  to  the  fact  that 
the  crane  girder  would  be  unnecessarily  heavy  if  a  longer  span  were 
used.  The  side  spans  are  usually  from  30  to  40  feet. 

In  case  it  is  desirable  to  have  the  building  wider  than  150  feet, 
and  still  have  it  lighted  by  natural  light,  the  common  saw-tooth  roof 
(Fig.  84)  or  Ketchum's  modified  saw-tooth  (Fig.  85)  is  used.  In  such 
cases  the  bays  are  seldom  greater  than  40  feet.  Cranes  may  be 
placed  in  one  or  all  of  the  bays.  One  great  advantage  of  this  type  of 
roof  is  that  it  gives  a  good  light  uniformly  throughout  the  entire  shop; 
and  at  any  time  it  is  desired  to  widen  the  shop,  additional  bays  may 
be  added.  The  shop  may  also  be  lengthened  by  adding  additional 
trusses  at  the  end.  Of  course,  shops  of  the  first  two  types  mentioned 
may  be  widened  by  addition  of  extra  bays;  but  the  connection  to  the 
old  work  will  be  unsatisfactory,  and  skylights  will  have  to  be  placed 
in  the  roofs  both  of  the  old  bays  and  of  the  new  ones.  For  views 
showing  the  interior  of  shops,  see  pages  77  to  84. 

20.  General  Requirements.    The  general  requirements  of  a  mill 
building  depend  in  detail  on  the  purpose  for  which  it  is  intended. 
The  requirements  which  are  common  to  all  classes  of  buildings  are 
ventilation,  good  light,  and  transportation  facilities  both  inside  and 
outside  the  shop.     The  question  of  light  and  ventilation  is  discussed 
on  pp.  42  and  66.      In  regard  to  transportation  facilities,  it  may  be 
said  that  either  the  building  should  be  placed  so  close  to  a  railway 
track  that  the  material  may  be  unloaded  by  means  of  a  crane  and 
hauled  into  the  shop,  or  the  track  must  run  into  the  shop  so  that  the 
material  may  be  unloaded  and  placed  on  the  stock  floor  by  means  of 
a  crane  in  the  center  bay  and  wall  jib-cranes  (see  Fig.  109,  p.  83)  or 
by  means  of  hand  trucks. 

21.  Layout.    The  purpose  for  which  the  building  is  intended, 
and  its  relative  location  in  regard  to  transportation  facilities,  will 
determine  its  layout.     For  manufacturing  purposes,  it  should  be  so 
laid  out  that  the  materials  will  always  pass  forward  in  going  from  the 
raw  material  to  the  finished  product.     In  general  it  may  be  said  that 
the  engines,  machines  (lathes,  milling  machines,  drill  presses,  shears. 


189 


68 


ROOF  TRUSSES 


Drills  ond  Shears 

'Engine  Room 
._     L 

"         "~                  1 
Laying  out          j 

Shipping  Dep't, 

Floor               ]  Erection  Floor 
Line  of  Ctlumns  ^ 

^Railroad  Track 

T 

Planers  and  Milling  Machines    j 

Stock  Room 

Fig.  86.    Layout  of  a  Frog  and  Switch 
Company's  Building. 


punches,  etc.),  and  stock  room,  should  be  in  the  side  bays;  and  the 

laying  out,  erection,  and  shipping  floors  should  be  placed  in   the 

center  bay  in  the  order  mentioned.     Fig.  86  gives  a  layout  of  a 

concern  manufacturing  frogs  and 
switches. 

22.  Framing.  The  framing 
of  a  mill  building  consists  of  the 
roof  framing,  which  has  been 
discussed  in  the  preceding  arti- 
cles; the  columns,  which  will  be 
discussed  in  the  next  article;  and 
the  girts  and  eave-struts. 
Eave-struts  are  a  detail  of  cornice  design.  Various  forms  and 

methods  of  connections  are  shown  in  Article  29,  p.  95,  and  the 

student  is  referred  to  this  article. 

Girts  may  be  made  of  wood,  angles,  or  channels.     They  should 

be  designed  for  a   pressure  of   from  20 

to  30  pounds  to  the  square  foot  on  the 

side  of   the   building.     The   spacing  of 

the  purlins  depends  upon  the  thickness 

of  the  corrugated  steel  used.  On  account 

of  the  fact  that  corrugated  steel  can  be 

procured  in  lengths  up  to  10  feet  and 

for  spans  of  5  feet,  the  stress  per  square 

inch  due  to  30  pounds  per  square  foot  is 

about  25  000  pounds.     In  No.  24  gauge 

corrugated  steel,  the  spacing  of  the  girts 

is  limited  to  5  feet  or  less. 

Corrugated  steel  may  be  fastened  to 

the  girts  by  barbed  roofing  nails  in  case 

the  girts  are  wood,  or  by  clinch  nails  in 

case  the  girts  are  angles,  or  by  clips  fas- 
tened with  rivets  or  TVinch  stove  bolts 

f   inch  long.      Nails    and   clinch  nails 

should  be  spaced  about  8  to   12  inches  apart.     Clips  are  made  of 

No.  16  gauge  steel  from  f  inch  to  2£  inches  wide,  and  are  spaced  8 

to  12  inches  apart.     Fig.  87  shows  girts,  together  with  the  method 

of  attaching  the  corrugated  steel.    The  number  of  nails,  rivets,  and 


0 

0 

^<%4^y 

™ 

>o 

0 

o 

o 

' 

*^HE 

0 

0 

5 

>0 

0 

0 

0 

i      ^ 

)° 

o 

0 

o 

CT>  ( 

0 

c 

o 

(0 

S< 

0 

f> 
o 

0 

Colum 

0 
0 

o 
o 

? 

CO 

—  ^ 

Jo 

o 

0 

0 

o 

0 

Fig.  87.    Methods  of  Connecting 
Corrugated  Steel  to  Girts. 


190 


ROOF  TRUSSES 


stove  bolts  in  a  pound  is  to  be  found  in  the  handbooks  of  various 
manufacturers. 

Window-frames  in  mill  buildings  are,  in  general,  similar  to  those 
placed  in  frame  or  brick  buildings.  These  frames  are  fastened  either 
directly  to  an  iron  framing  or  to  wood  nailing-pieces  placed  on  the 
iron  framing.  The  win- 
dows may  be  glazed  in  the 
usual  fashion  by  means  of 
putty,  or  may  have  the 
glass  held  in  place  by  some 
of  the  methods  shown  in 
Fig.  73,  p.  44.  Windows 
in  the  side  of  the  shop 
may  be  so  fixed  that  they 
may  be  raised  and  lowered 
as  the  ordinary  dwelling 
window;  or  they  may  slide 
horizontally;  or,  again, 
they  may  be  fixed  so  that 
they  cannot  be  moved. 
The  windows  in  the  moni- 
tors are  usually  fixed  with 
a  swinging  sash  which  can 
be  operated  from  the  floor 
of  the  shop  (see  Fig.  89). 

The  glass  in  the  win- 
dows may  be  the  common 
window  glass,  common 
plate  glass,  ribbed  or  cor- 
rugated glass,  wire  glass, 
or  prisms.  Of  these  va- 
rieties, the  prisms  and  the  ribbed  or  corrugated  are  the  best, 
since  they  give  a  more  uniform  light  and  are  not  easily  broken. 
Wire  glass,  which  is  made  of  wire  netting  moulded  in  the  middle  of 
the  sheet  of  glass,  gives  a  very  good  light,  and  has  the  additional 
advantage  that  it  does  not  crack  and  fall  out  under  the  action  of 
file  and  water.  It  is  considered  fireproof.  Common  window  glass 
does  not  diffuse  the  light  so  well  as  most  of  the  other  glasses.  It  is 


Fig.  88.  Section 

siidmg- 

Window. 


Fig.  89.    Section  of  a  Monitor 
Swing  Window. 


191 


70 


ROOF  TRUSSES 


very  liable  to  fracture,  and  for  this  reason  the  inside  of  the  window 
should  be  covered  with  wire  netting.  Prisms  are  made  by  the 
American  Luxfer  Prism  Company,  of  Chicago.  They  may  be 
obtained  up  to  84  inches  in  width  and  36  inches  in  height.  The 
width  is  parallel  to  the  saw  teeth.  Figs.  88  and  89  give  sections 
of  windows,  showing  the  framing.  Attention  is  called  to  the  fact  that 
the  roof  on  the  monitor  should  overhang  sufficiently  to  prevent  the 

water  from  dropping 
upon  the  swinging  win- 
dow when  it  is  fully 
opened. 

Doors  may  consist 
entirely  of  wood,  of  a 
frame  of  angles  covered 
with  corrugated  steel, 
or  of  corrugated  steel 
alone.  The  first  two 
classes  may  be  so  fixed 
that  they  will  slide,  as 
in  the  folding  doors  of 
residences;  open  out- 


ward  like  a  common 
door;  lift  vertically;  or, 
in  case  they  are  made 
entirely  of  corrugated 
steel,  roll  up  like  a  win- 
dow-shade. This  latter  door  is  a  patented  one.  Shop  doors  are 
seldom  made  to  open  outward  or  inward,  on  account  of  the  space 
required — a  space  which  can  be  devoted  to  better  purposes.  Figs. 
90,  91,  and  92  show  details  of  the  above  doors. 

Let  it  be  required  to  design  the  girt  when  the  trusses  are  16 
feet  apart  and  the  girts  are  5  feet  center  to  center.  The  moment 
.g  5  X  1G  X  30  X  16  X  12  =  ^  ^  pound-inches;  and  the  re- 
57600 


Fig.  90.    Detail  of  a  Wooden  Door. 


quired  section  modulus  is 


15000 


3.84.   By  inspecting  the  tables* 


in  the  Carnegie  Handbook,  pp.  97  to  119,  it  is  found  that  the  fol- 
lowing shapes  will  be  sufficient: 


192 


ROOF  TRUSSES 


71 


SECTION  MODULUS 


One  5-inch  9.75-pound  I-beam 

One  6-inch  8. 00-pound  channel 

One  4TV  by  3^-inch  10 . 3-pound  zee-bar 

One  6  by  4  by  TVmch  14 . 3-pound  angle 


4.80 
4.30 
3.91 
3.83 


From  this  it  is  evident  that  the  channel  is  the  most   efficient  and 
economical. 

23.  Columns.  Columns  may  consist  of  almost  any  combina- 
tion of  shapes,  either  latticed  or  connected  by  plates.  Some  of  the 
most  common  cross-sections  are 
shown  in  Fig.  93,  those  illustrated 
in  b  and  c  being  used  to  a  great 
extent.  The  advantage  of  these 
forms  is  that  they  give  a  small 
radius  of  gyration  about  the  axis 
b-b,  and  a  larger  one  about  the 
axis  a-a  (see  Fig.  94).  This  is 
especially  desirable,  since,  in  ad- 
dition to  the  direct  stress  due  to 
the  weight  of  the  cranes,  roof 
truss,  and  covering,  the  column 
must  withstand  the  moment  due 
to  the  wind  and  to  the  eccentric- 
ity of  the  runway  girder.  Both 
of  these  moments  tend  to  bend 
the  column  around  the  axis  a-a. 
The  bending  moment  due  to  the 
eccentricity  of  the  runway  girder 
is  equal  to  the  reaction  of  the 
girder,  times  the  distance  from  the  center  of  the  column  (see  Figs. 
95  and  96).  In  case  the  details  of  the  column  are  as  given  in 
Fig.  96,  the  direct  load  due  to  the  reaction  of  the  truss  and  its 
covering  produces  a  moment  due  to  its  eccentricity.  This  moment 
is  Rt  X  er  Since  R^  acts  on  the  opposite  side  of  the  center 
of  the  column  from  the  point  of  action  of  Rs,  it  tends  to  counteract 
the  effect  of  the  moment  due  to  the  eccentricity  of  the  runway  girder. 
The  total  moment  due  to  eccentricity  is  J/.  =  Rt  X  el  -  RKX  e.  If 


Fig.  91.    Detail  of  Vertical  Hoist  Door. 


193 


72 


ROOF  TRUSSES 


the  first  term  of  this  equation  is  less  than  the  last  term,  the  compres- 
sive  stress  on  the  side  of  the  column  with  the  runway  girder  is  increased, 
and  vice  versa.  The  stress  in  the  column  from  the  runway  girder 


Pig.  92.    Detail  of  Rolling  Door  of  Corrugated  Steel. 
Courtesy  of  Kinnear  Mfg.  Co.,  Columbus,  Ohio. 

to  the  roof  is  that  due  only  to  the  vertical  reaction  of  the  roof  and  the 
bending  due  to  the  wind.  In  that  part  of  the  column  below  the  crane 
girder,  the  stress  is  that  due  to  the  direct  action  of  the  weight  of  the 
roof;  its  eccentricity,  if  there  be  any;  the  direct  action  and  eccen- 
tricity of  the  runway  girder;  and  the  bending  moment  due  to  the  wind. 
The  bending  moment  due  to  the  wind  is  less  in  this  part  of  the 

H  H  n  ii  n 

a  b  c  d  e  f 

Fig.  93.    Cross- Sections  of  Columns. 

column  than  it  is  at  the  foot  of  the  knee-bracing,  but  it  is  customary 
to  consider  it  the  same. 

In  order  to  prevent  eccentric  stresses  due  to  the  reaction  of  the 
runway  girder,  an  extra  column  to  carry  the  crane  girder  is  placed 
alongside  the  roof  column  (see  Figs.  100  and  117,  pp.  75  and  88). 
This  is  much  used  by  A.  F.  Robinson,  Bridge  Engineer  of  the  Atchison, 
Topeka  &  Santa  Fd  Railroad  System,  who  claims  it  to  be  a  very 


194 


ROOF  TRUSSES 


73 


Fig.  94.    Illustrating  the  Two  Radii  of 
Gyration. 


Fig.  95.    Runway-Girder  Eccentricity. 


economical  and  efficient  detail.  One  advantage  of  this  is,  that,  if  at 
any  time  it  is  desirable  to  use  a  heavier  crane,  this  column  can  be 
removed  and  a  stronger  one  put  in  its  place, 
without  in  any  way  affecting  the  remainder 
of  the  building* 

In  order  to  illustrate  the  design  of  a 
column,  let  it  be  required  to  design  a  col- 
umn with  detail  as  shown  in  Fig.  95,  the 
height  being  20  feet,  the  distance  of  the  run- 
way girder  from  the  face  of  the  column  8 
inches,  the  direct  stress  15  600  pounds,  and 
the  bending  moment  due  to  the  wind 
924  000  pound-inches.  The  reaction  of  the 
runway  girder  is  20  000  pounds.  The  stress 
due  to  the  bending  moment  caused  by  the 
wind  and  the  eccentricity  of  the  runway 
girder  must  be  worked  out  by  formula  8, 
"Strength  of  Materials,"  p.  86;  and  to  this 
must  be  added  the  direct  stress  caused  by 
the  weight  of  the  roof  and  the  crane-girder 
reaction. 

Since,  according  to  Article  13,  the  unit- 
stress  must  be  reduced  one-half  in  deter- 
mining  the  section  to  withstand  stresses  due  to  crane  loads,  the 
moment  due  to  the  crane  loads  and  also  its  direct  action  must  be 


Fig.  96.    Runway-Girder  and 
Roof-Truss  Eccentricity. 


195 


74 


ROOF  TRUSSES 


Fig  97.    Illustrating  Problem  on 
Page  73. 


multiplied  by  2  in  order  that 
the  same  formula  for  the  unit- 
stress  may  be  used  throughout 
in  the  design  of  the  column. 

Let  four  5  by  3^  by  f-inch 
angles  with  a  16  by  f-inch  web 
plate  be  assumed,  and  placed 
as  shown  in  Fig.  97.  These 
angles  have  an  area  of  3.05 
square  inches  each;  and  a 
moment  of  inertia  parallel  to 
the  long  leg,  of  3  18.  Then 
(see  "Strength  of  Materials," 
pp.  48-53),  the  moment  due 
to  crane  reaction  is  20  000  X 
(8.125  +  8)  =  322  500  pound- 
inches.  Accordingly,  in  using 
this  in  the  formula,  it  will  be 
2  X  322  500  =  645  000  pound-  Anchor  ^ 
inches;  and  this,  added  to  the 
924  000  pound-inches  due  to 
the  wind,  will  make  a 
inches. 


'  Runway 
Girder 


2-0*' 


Holes 

'    Fig.  98.    Detail  of  Column. 

total  bending  moment  of  1,569,000  pound- 


196 


ROOF  TRUSSES  75 

7(l-a  =  4  X  3.18  +  4  X  3.05  X  7.2652+  ^^  =  784.72, 


784.72 


V  4X  3.05  +  f  X  16 
The  allowable  unit-stress  is: 


=  6.56 


20  V  1 2 
P  =  24  000  -  110  X  — =  19  975  pounds  per  square  inch. 


Fig.  99.    Detail  of  Column. 


Fig.  100.    Detail  of  Column. 


The  actual  unit-stress  (see  "Strength  of  Materials,"  p.  86),  is: 

16.25 


„      15600  +  2  X  20000 


1  569000   X 


4  X  3.05  +  f  X  16         7S4  72      (15  600  +  2  X  20  OOP)  (20  X  12)2 

10  X  28000000 
3024  +  16420 
19  444  pounds  per  square  inch. 


197 


76 


ROOF  TRUSSES 


Since  this  is  slightly  less  than  the  allowable  stress,  19  975  pounds 
per  square  inch,  this  section  is  the  correct  one. 

Details  of  columns  are  shown  in  Figs.  98,  99,  and  100.  In  case 
the  column  is  considered  fixed  at  its  base,  the  base  of  the  column  is 
usually  made  as  shown  in  Fig.  99.  Long  bolts  deeply  imbedded  in 
the  masonry  are  run  up  through  the  holes  a ;  a  heavy  washer  is  placed 
over  the  bolt,  and  the  nut  screwed  down  tightly.  Each  bolt  must  be 
designed  to  withstand  a  stress  of  H2  X  n  -T-  2d  (see  Figs.  43  and  99). 
24.  Knee=Braces.  The  determination  of  the  stresses  in  knee- 
bracing  has  been  made  in  Article  9.  Knee-braces  consist  of  two 

angles  placed  back  to  back,  and 
are  joined  to  the  column  and  roof 
truss  as  shown  in  Fig.  101  and 
in  the  figures  showing  cranes. 
They  must  be  designed  to  with- 
stand the  greatest  compressive 
stress ;  and  must  also  be  examined 
to  see  if  they  are  safe  in  tension, 
since  they  are  under  either  tensile 
or  compressive  stresses  according 
to  the  direction  in  which  the  wind 
blows. 

The  knee-brace  for  the  truss- 
bent  of  Article  9  will  now  be 
designed.  The  maximum  com- 
pressive stress  is  21  440  pounds. 

The  radius  of  gyration  must  be  at  least  131  --  120  =  1.09.  Two 
angles  3^  by  3  by  TVmch,  placed  back  to  back  with  their  longer 
legs  |  inch  apart,  will  be  assumed,  since  they  are  the  smallest  size  to 
be  used  with  r  =  1 .09  or  greater.  The  radius  of  gyration  about  an 
axis  perpendicular  to  the  longer  legs  is  1 . 10;  and  the  allowable  unit- 


Fig.  101.    Detail  of  Knee-Brace  and 
Connections. 


stress  is  P  =  24  000  - 


110  X  131 
110 


=    10900    pounds   per 


square 
21  440 


inch,     the  length  being  131  inches.     The  required    area  is  -r, 

,  •  iu  yu(j 

=  1.97  square  inches.  Since  this  is  less  than  the  given  area,  and 
since  the  angles  are  the  smallest  allowed,  these  angles  are  suffi- 
cient. The  maximum  tensile  stress  is  8  640  pounds,  and  the  required 
net  area  is  8  640  H-  15  000  =  0.58  square  inch.  The  net  area  given 


198 


ROOF  TRUSSES 


77 


by  the  angles  is  3.86  -  0.55  =  3.31  square  inches,  two  f-inch  rivet- 
holes  being  taken  out.  This  shows  the  angles  to  be  amply  safe  in 
tension,  and  they  will  therefore  be  used  for  the  section  of  the  knee- 
braces. 

25.     Runway  Girders.    The  runway  girders  extend  from  column 
to  column  on  each  side  of  the  bay  in  which  the  girder  runs.    An 


Fig.  103.    Electric  I-Beam  Hoist,  One-Motor. 
Courtesy  of  Case  Manufacturing  Company,  Columbus,  Ohio. 

inspection  of  the  figures  of  this  article  will  give  a  clear  idea  of  their 
position  and  their  details.  Along  these  girders  run  the  wheels  which 
support  the  end  of  the  crane.  The  crane  may  be  a  small  hoist,  as 
indicated  in  Figs.  102,  103,  and  104,  in  which  case  the  crane  girder 
consists  of  a  simple  I-beam  supported  by  two  wheels  at  the  ends,  and 
these  are  placed  close  together.  In  other  cases  the  crane  consists  of 


199 


78 


ROOF  TRUSSES 


Fig.  103.    Electric  I-Beam  Hoist. 
Courtesy  of  Marts  Brothers,  Philadelphia,  Pennsylvania. 


two  girders  placed  side  by  side,  upon  which  runs  the  carriage  carrying 
the  hoist.  This  type  of  crane  is  supported  upon  four  to  eight 
wheels  (see  Figs.  105,  106,  107,  108,  109,  and  110). 

The  maximum  bending  moment  and  shear  in  a  runway  girder 


Fig.  104.    Small  Electric  I-Beam  Hoist;  Capacity  500  Lbs. 
Courtesy  of  Pawling  &  Harnischfeger,  Milwaukee,  Wis. 


200 


201 


202 


203 


204 


ROOF  TRUSSES 


83 


will  depend  upon  the  capacity  and  span  of  the  crane,  and  also  upon 
the  distance  apart  of  the  wheels  at  its  ends.  Where  the  bending 
moment  is  not  too  great,  the  runway  girders  may  be  composed  of 
channels  or  I-beams  (see  Figs.  103,  104,  and  106).  In  case  the 
moment  is  too  great  to  make  the  use  of  these  possible,  the  runway 
girders  are  composed  of  plate-girders  (see  Figs.  105,  107  to  11CV 


Fig.  109.    Wall  Jib-Crane,  Electrically  Operated;  Capacity,  10,000  Lbs. 
Courtesy  of  Pawling  &  Harnischfeger,  Milwaukee,  Wisconsin. 

Plate-girders  consist  of  a  flat  plate  called  a  web  plate,  which  has 
riveted  to  it  at  its  upper  and  lower  edges  two  angles,  or  two  angles 
and  one  plate,  called  the  cover-plate.  The  angles  are  called  flange 
angles;  and  the  two  angles  together,  and  the  cover-plate  when  used, 
are  called  the  flanges.  At  certain  distances  along  its  length,  equal 
to  or  less  than  its  depth,  vertical  angles  are  riveted  on  opposite  sides 
of  the  web  plate.  These  are  called  stiff  eners,  their  function  being  to 
stiffen  the  web  under  the  action  of  the  shear.  See  Fig.  1 1 1  for  a 
general  view  of  a  plate-girder,  together  with  the  names  of  the 
various  parts. 


206 


ROOF  TRUSSES 


85 


Top  Flanqe 


Bottom  Flange  J    \  Sechon  o-a 

Fig.  111.    Plate-Girder  Notation. 

P  P 


=>          P 

| 

4F 

X 

F                         X 

f 

> 

x- 

"N 

"\            /T\ 

^ 

2 

—  2 

v 

7  H) 

L^-2 

L4- 

Z             ' 

1                       L 

. 

P    P      P     P 


P    P 


F 

G 

F 

>^ 

) 

tS 

^>     J 

s^ 

Fig.  112.    Position  of  Crane  Truck  for  Max-     Fig.  113.    Position  of  Crane  Truck  for  Max- 
imum Eud  Shear  of  Kunway  Girder.  imum  Moment  in  Runway  Girder. 


Fig.  114.    Position  of  Crane  Truck  for  Max-     Fig.  1 15.    Position  of  Crane  Truck  for  Max- 
imum Reaction  on  Column.  imum  Shear  at  any  Section. 

The  maximum  shear  in  the  runway  girder  will  occur  when  the 
crane  wheels  are  in  the  position  shown  in  Fig.  112;  and  the  maximum 
moment  will  occur  under  the  wheel  nearest  the  middle  of  the  span, 
when  the  wheels  are  in  the  position  shown  in  Fig.  113.  The  maxi- 
mum reaction  of  the  runway  girders  on  the  column  will  occur  when 
the  wheels  are  in  the  position  shown  in  Fig.  114.  In  order  to 


207 


TABLE  XIV 
Maximum  Crane  Reaction 


5  to  60  Tons 


60  to  150    Tons 


g 

2 

I 

r  * 

J5 

A 

• 

C 

D 

K 

F 

c 

WHEEL   TRAM  RAIL 

H 

^K 

< 

LOAD 
(in  Ibs.) 

AM.  STD. 

11 

CT 

<B 

in. 

ft.      in. 

ft.      in. 

ft.    in.  ft.    in. 

ft.      in. 

ft.in. 

ft.in. 

10 

7 

4-  54 

<1-  8 
12-  0 

7 

7-  64 

10  000  34-1  1-  40 

1-  5 

5 

60 

8 

4-  74 

I  1-11 
1  2-  1 

5 

9-  0 

12500 

80 

8 

4-  84 

(1-11 
\2-2 

4 

9-  31 

15  500 

10 

8 

5-  0} 

fl-  0 

la-  4 

9 

8-  54 

16500 

34-11-  40 

1-  0 

10 

60 

8 

4-111 

11-111 

12-  4 

10 

9-  71 

19  500 

80 

8 

5-  04 

1-114 

(2-  44 

9 

9-  94 

23000 

40 

8 

5-  4} 

52-  o 

1  2-  9 

1-34 

2-  0 

9-  6 

24  500 

3J-2  J-  50 

1-  3 

15 

60 

8 

5-  41 

n'2-  0 
2-  9 

1-34 

2-  0 

10-  74 

28000 

80 

8 

5-  54 

ItJ 

1-2* 

2-  0 

10-  94 

31  500 

40 

8 

5-  54 

(2-0 
12-  9 

1-61 

2-  0 

9-  6 

30000 

3J-2i-  50 

1-  3 

20 

60 

8 

5-  54 

JfcJ 

1-61 

2-  0 

10-  74 

34000 

80 

9 

5-  64 

/2-  Oi 

12-9 

1-51 

2-0 

11-  14 

38000 

40j  9 

6-  01    2-  6 

3-91,2-  74 

11-  Ql 

38  600 

41-2f-  60|l-  3 

25 

601  9 

6-  Oil  2-  6 

3-912-  74 

11-  34 

42  400 

8010 

6-  21 

2-  6 

3-71|  2-  74 

11-  84 

47  000 

4010 

6-  3f 

2-  7 

3-84'2-10 

11-  44 

45  600 

41-2$-  60 

1-  3 

306010 

6-  3| 

2-  7 

3-84 

2-10 

11-  64 

49  600 

8010 

6-  3J 

2-  7 

3-84 

2-10 

12-  0 

54  600 

40 

40'11 
60  11 
80,11 

7-  44 
7-44 
7-  44 

3-  14 
3-  14 

3-  14 

4-24 
4-24 
4-24 

3-  84 
3-  84 
3-  84 

12-  8 
13-  0 
13-  5 

59  600 
64000 
70000 

5  -24-  80 

1-  6 

50 

4013 
6013 

7-114 
7-114 

3-  6 
3-  6 

4-04 
4-04 

3-  9 
3-  9 

13-104 
13-104 

77000 
84600 

5J-2|-100 

1-  G 

8013 

7-114 

3-  6 

4-04 

3-  9 

14-  0 

92000 

60 

4014 

6014 

8-  7J 
8-  71 

4-  1 
4-   1 

4-31 

4-3J 

4-  44 
4-  44 

15-  2 
15-  2 

88000 
94000 

5f-2J-100 

1-11 

8014 

ft-  7| 

4-  1 

4-3J 

4-  44 

15-  4 

103  000 

60 

40  12$  10-  31 
60  124  10-  3} 
80.12410-  31 

4-  0 
4-  0 
4-  0 

2-7J 

2-7J 
2-7f 

4-  44 
4-  4% 
4-  44 

3-  6 
3-  6 
3-  6 

5-4 
5-4 
5-4 

44  000  5f-2f-100 
47  0006  -4  -150 
51  500 

4012411-  3 

4-  6 

3-84 

4-  04 

5-  0 

6-0 

55  000  5f-2f-100  2-  2 

75 

6012*11-  3 

4-  6 

3-84 

4-  04 

5-  0 

6-0 

60  000,6  -4  -150 

8012411-  3 

4-  6 

3-84 

4-  04 

5-  0 

6-0 

64000 

4016} 

13-  21 

4-   1 

2-0 

SPECIAL 

5-  0 

6-0 

83000 

6  -4  -150 

4-  7 

00 

60164 

13-  21 

4-  1 

2-0 

' 

5-  0 

6-0 

86000 

80164 

13-  21 

4-  1 

2-0 

' 

5-  0 

6-0 

89000 

40'l7 

15-  6| 

6-  0 

3-2 

' 

6-  0 

6-0 

130  000 

6  -4  -150 

4-  7 

150 

6017 

15-  6| 

6-  0 

3-2 

' 

6-  0 

6-0 

134000 

8017 

15-  6* 

6-  0 

3-2 

' 

6-  0 

6-0 

139  000 

ROOF  TRUSSES 


87 


TABLE  XV 
Typical  Electric  Cranes 


CAPACITY 
(Tons) 

SPAN 
(Ft.) 

WHEEL  BASE 
F 

WHEKL  LOAD 
P 

A+2in. 

B 

WEIGHT  of  RUNWAY  RAIL 

For  Plate-Girders 

I-Beams 

5 

40 

8  ft.  6  in. 

12000 

10  in. 

7ft 

.     40  Ibs.  per  vd. 

40  Ibs. 

60 

9 

'     0 

* 

13000 

10  ' 

7" 

40 

40    " 

10 

40 

9 

0 

19000 

10 

7 

45 

40 

< 

60 

9 

6 

21  000 

10 

7 

45 

40 

15 

40 

9 

6 

26000 

10 

7 

50 

50 

< 

60 

10 

0 

29  000 

10 

7 

50 

50 

* 

20 

40 

10 

0 

33  000 

12 

8 

55 

50 

i 

60 

10 

6 

36000 

12 

8 

55 

50 

« 

25 

40 

10 

0 

40  000 

12 

8 

60 

50 

i 

60 

10 

6 

44000 

12 

8 

60 

50 

« 

30           40 

10 

6 

48000 

12 

8 

70 

60 

« 

60   j  11 

0 

52  000 

12 

8 

70 

60 

« 

40           40      11 

0 

64  000 

14 

9 

80 

60 

i 

60  j  12 

0 

70  000 

14 

9 

80 

60 

« 

50          40 

11 

0 

72  000 

14 

9 

100 

60 

'  . 

J60 

12 

0 

80  000 

14 

9 

100 

60 

' 

obtain  the  maximum  shear  at  any  section,  as  a-a,  the  load  should 

be  placed  as  shown  in  Fig.  115;  and  the  maximum  shear  will  then  be 

p 

/,  for  two  wheels; 


Lowest  point  of  truss 


the  left  reaction,  which  is  R  =  2P  (x  +  — ) 
and  R  =  4  P  (x  +  F  +  ~)  -=-  /,  for  four  wheels. 

The  values  of  P  for  traveling  cranes  of  various  capacities  and 
spans  may  be  obtained  upon  writ- 
ing to  the  various  crane  manufac- 
turing companies,  whose  addresses 
will  be  found  in  the  advertising 
sections  of  the  engineering  peri- 
odicals. The  distances  between 
wheels  may  be  obtained  from  their 
catalogues,  which  may  be  had  upon 
application.  The  values  of  P,  and 
the  distances  between  wheels  for 
cranes  of  various  spans  and  ca- 
pacities, are  given  in  Table  XIV, 
which  is  made  from  information  furnished  through  the  courtesy  of 
Pawling  &  Harnischfeger,  Milwaukee,  Wisconsin. 

The  values  in  Table  XV  are  taken  from  the  "Transactions"  of 


Fig.  1 16.    Showing  Notation  used  in 
Table  XV. 


209 


210 


ROOF  TRUSSES  89 

the  American  Society  of  Civil  Engineers,  Vol.  54,  p.  400,  1905.  They 
are  for  typical  traveling  electric  cranes,  and  are  proposed  by  Mr.  C.  C. 
Schneider,  one  of  the  most  distinguished  of  structural  engineers. 

The  side  clearance  B  from  the  center  of  the  rail,  and  the  vertical 
clearance  of  the  beam  from  the  top  of  the  rail,  are  given  in  this  table 
(see  Fig.  116).  These  values  for  the  cranes  of  different  manufacturers 
may  be  obtained  from  their  catalogues;  and  they  must  be  known,  in 
order  that  the  crane  shall  not  interfere  with  the  columns  or  the  roof 
trusses. 

If  the  runway  girder  is  composed  of  an  I-beam,  a  channel  is 
usually  riveted  to  its  top;  and  on  this  the  rail  on  which  the  crane 
wheels  move  is  fastened  down  at  intervals  (see  Fig.  107)  of  about 
21  or  3  feet.  Figs.  106  and  117  show  details  of  this  kind  of  girder. 
Note  that  the  rails  are  U-shaped  (see  Fig.  105).  This  rail  is  used 
extensively,  although  in  many  cases  the  common  T-rail  is  used  and  is 
fastened  down  by  means  of  clamps  around  the  edge  of  the  flange  of 
the  girder  (see  Fig.  110). 

In  case  plate-girders  are  necessary  for  runway  girders,  they 
must  be  designed.  The  depth  of  these  girders  should  be  ^  to  ^  of 
the  distance  between  trusses  or  columns  —  that  is,  TV  of  their  span; 
The  depths  must  be  in  the  even  inch.  For  example,  if  the  trusses 
were  16  feet  apart,  the  depth  of  the  girder  would  be  16  -f-  10  =  1.6 
feet,  which  is  equal  to  19.2  inches.  The  depth  of  the  girder  must 
then  be  made  20  inches,  since,  if  it  were  made  19  inches,  it  would 
be  difficult  to  obtain  a  web  plate  19  inches  wide,  for  the  mills  do  not 
as  a  rule  have  plates  of  odd-inch  widths  in  stock. 

The  thickness  of  the  web  plate  is  given  by  the  formula  : 


but  in  no  case  shall  it  be  less  than  T5T  inch.  In  this  formula,  Va 
is  the  maximum  end  reaction  of  the  runway  girder.  It  is  equal 
to  R  as  given  by  the  formula  on  p.  87,  when  x  is  equal  to  I  —  F,  and 
d  is  the  depth  of  the  girder,  which  is  equal  to  the  depth  of  the  web 
plate,  and  Sa  is  the  unit  allowable  shearing  stress. 

The  flanges  are  composed  of  two  angles,  placed  with  the  long 
legs  horizontal  in  case  unequal-legged  angles  are  used.  The  required 
net  area  of  one  flange  is  given  by  the  formula  : 

A        M~ 
A~S,(d-2)' 


211 


90 


ROOF  TKUSSES 


3rd.      4th.      5tK. 


Fig.  118.    Position  of  Tenth-Points. 


in  which  Mm  is  the  moment  obtained  when  the  wheels  are  in  the 
position  shown  in  Fig.  113,  <St  is  the  unit  allowable  tensile  stress,  and 
d  is  the  width  of  the  web  plate.  If  the  area  A  has  been  computed, 
two  angles  must  be  found  from  the  tables  in  the  Carnegie  Handbook, 

such  that  when  one  |-inch  or 
f-inch  rivet-hole,  as  the  case 
may  be,  is  taken  out,  each  angle 
will  give  a  net  area  equal  to  or 
slightly  in  excess  of  the  area  4 1 . 
These  flange  angles  must  be 
riveted  to  the  web  by  rivets 
placed  a  certain  distance  apart. 

For  convenience  of  manufacture,  the  girder  is  divided  into  ten  equal 
parts,  and  the  rivet  spacing  between  any  two  of  these  divisions — or 
tenth-points,  as  they  are  called — is  kept   the  same.     These  tenth- 
points  are  numbered  (see  Fig.  118).     The  rivet  spacing  in  the  first 
division    is    the 
same  as  that  com- 
puted for  the  end 
of  thegirder,  which 
is  the  zero   tenth- 
point;    the    rivet 
spacing  in  the  sec- 
ond division  is  the 
same  as  that  com- 
puted for  the  1st 
tenth-point;    and 
so  on.     The  rivet  spacing  at  any  point  is  given  by  the  formula: 

S 


i!?.  1 19.    Determination  of  Distance  between  Gauge  Lines. 


V  &)•+(£ 


in  which, 

Fx  =  Maximum  shear  at  the  point; 

v     =   Maximum  allowable  stress  on  one  rivet;    this  will  be  the  bear- 
ing value  of  the  rivet  in  the  web  plate  (see  Table  X,  p.  47); 
P    =  Maximum  reaction  of  one  crane  wheel  (see  Table  XIV  or  XV;; 
/ig    =-=  Distance  between  gauge  lines  of  the  angles. 

In  case  there  are  two  gauge  lines  on  the  angle,  then  the  distance  hg  is 
the  distance  between  centers  of  these  gauge  lines  (see  Fig,  119). 


212 


ROOF  TRUSSES 


91 


Table  IX,  p.  46,  gives  the  gauge  lines  for  different  lengths  of  angle 
legs.  If  S  gives  a  value  less  than  2f  inches,  the  leg  of  the  angle  agamst 
the  web  must  be  5  inches  or  more,  on  account  of  practical  limitations 
of  manufacture. 

26.  Examples.  In  order  to  illustrate  the  preceding  methods, 
two  problems  will  be  worked  out. 

1.  Design  a  runway  girder  for  a  5-ton  crane  of  40-foot  span,  the 
wheel  loads  and  wheel  base  being  as  given  in  Table  XV,  p.  87,  and  the  dis- 
tance between  trusses  20  feet. 

In  order  to  produce  the  maximum  moment,  the  wheel  must  be 
placed  as  shown  in  Fig.  120.  The  left  reaction  is  12000  (2.125  + 
10.00  +  3.625)  -20  =  9450.  The  moment  under  wheel  1  is 
9450  X  7.875  X  12  =  894000  pound-inches,  which  requires  a  sec- 
tion modulus  of  894000  -^  15  000  -  59.60.  Looking  in  the  Car- 


7.8751    ^ 

6.5' 

^3.62 

2125'    6.375' 

1 

10'                 \t             10' 

20' 

7.25'    •" 

no' 

8 

c^ 
iT) 

175 

2.7  ^ 

1       8.25' 

10' 

10' 

20' 

Fig.  130.    Position  for  Maximum  Moment 
for  Problem  1  on  Page  91. 


Fig.  121.    Position  for  Maximum  Moment 
for  Problem  2  on  Page  91. 


negie  Handbook,  pp.  97  and  98,  it  is  seen  that  a  15-inch  42-pound 
I-beam  with  a  section  modulus  of  58.9  will  be  sufficient,  since  the 
section  modulus  is  less  than  2£  per  cent  under  that  required. 

2.  Design  a  runway  girder  for  a  30-ton  crane  of  60-foot  span,  the 
wheel  loads  and  wheel  base  being  as  given  in  Table  XV,  and  the  distance 
between  trusses  20  feet. 

The  wheels  are  placed  in  position  as  shown  in  Fig.  121.    The 


left    reaction    is 


52000(12.75  +  1.75) 
20 


37  700  pounds;   and  the 


maximum  moment,  which  occurs  under  wheel  1,  is  37  700  X  7.25  X 
12  =  3  285  000  pound-inches.  The  maximum  shear  occurs  when 
the  wheels  are  in  position  as  shown  in  Fig.  112,  p.  85,  and  is  75400 

pounds.    The    required   thickness   of    the    web   is  = 

0.314  inch,  the  depth  being  20  -r-  10  =  2  feet  =  24  inches.  The 
web  will  be  made  24  inches  wide  and  f  inch  thick. 


213 


92 


ROOF  TRUSSES 


The  required  net  flange  area  is 


3  285  000 


15  000  X  (24 -2) 
inches  for  two  angles,  or  4 . 99  square  inches  for  one  angle.  An  angle 
6  by  6  by  ^-inch  gives  a  gross  area  of  5 . 75  square  inches  and  a  net 
area  of  5.75  —  0.50  =  5.25  square  inches,  one  f-inch  rivet-hole  being 
taken  out  of  the  section.  Since  this  area  coincides  quite  closely 
with  the  required  area  and  is  larger,  it  will  be  used.  A  6  by  3^  by  f- 
inch  angle  would  have  been  better  in  regard  to  area,  but  the  rivet 
spacing  is  less  than  2f  inches  at  the  end,  and  this  required  a  double 
gauge  line  and  therefore  a  leg  5  inches  or  over. 

The  maximum  shears  at  the  tenth-points  are  now  computed, 
and  are  tabulated  as  follows: 

V0  =  75  400  pounds. 

Vj,  =  65  000 

V2  =  54  600 

V3  =  44  200 

F4  =  33  800 

Fs  =  26  000        " 

The  value  of  the  shear  to  be  used  in  any  particular  case  is  given 


All  Stiffeners 
-- 


2V 


Spocinq 


Fig.  122.    Stress  Sheet  of  Runway  Girder  of  Problem 
2  on  Page  91. 


Fig.  123.    Determination  of 
Size  of  Stiflener. 


above.     In  this  case,  P  —  52  000  pounds  ; 
v  =  6  570  pounds,  f-inch  rivets  being  used  ; 

and  /jg  is  24|-  —  2  I  2|  +  ~  1  =  17.5  inches.   The  rivet  spacing 
the  first  division  or  first  two  feet  of  the  span  is  : 


for 


V( 


75  400V       /52000Y 
17.5  )   +  V    30     ) 


=  1.414,  say  l£  inches. 


The  rivet  spacing  for  the  other  divisions  may  be  computed  by  the 
student.  It  is  given  in  Fig.  122.  The  web  of  the  girder  should  be 
stiffened  as  shown  in  the  figure,  by  angles  placed  as  there  indicated 
The  thickness  of  the  angles  should  not  be  less  than  ^  inch,  nor 
greater  than  \  inch.  The  size  of  the  angles  should  be  such  that  the 


214 


ROOF  TRUSSES 


93 


Flashing 


Flashing  J 


Fig.  124.    Section  of  Glass  Louvres  iu          Fig.  125.    Section  of  Metal       Fig.  126.    Section  of  Open 

Monitor.  T^nTr**^.  ivi    AyT~»^«.~«  ft* j*_-.  " 


Louvres  in  Monitor. 


Roof  SteeU    Clinch  Rivet 


Top  Chord 
of  Truss 


ig.  127.  Gable  Details  for  Corrugated  Steel. 


Roof  Steel  ->      Clinch 


nish 


Wall 
Fig.  128.    Gable  Details  for  Corrugated  Steel. 


215 


94 


ROOF  TRUSSES 


Fig.  129.    CorDice  Details  for  Steel  Roof. 
Figs.  130  and  131. 


outstanding  leg  does  not  reach  beyond  the  leg  of  the  flange  angle 
(see  Fig.  123).  This  makes  their  size  as  shown  in  Fig.  122.  The 
crane  rail  may  be  connected  directly  to  these  and  the  flange  angles ; 
or  a  channel  may  be  placed  over  the  flange  angles  and  riveted  to  them 
in  a  manner  similar  to  that  employed  in  the  case  of  I-beams,  the 

crane  rail  being  fastened 
to  that.  If  this  latter 
detail  is  employed,  the 
area  of  the  channel  is 
reckoned  as  forming  part 
of  the  upper  flange;  and 
the  net  area  of  the  angle 
must  then  be  equal  to  the 
required  net  area,  less  the 
net  area  of  the  channel. 
27.  Ventilators.  Mill 
buildings  may  be  venti- 
lated by  means  of  small 
circular  ventilators  such 
as  shown  in  Fig.  69,  p. 
41,  placed  at  certain  in- 
tervals along  the  ridge  or 

peak  of  the  roofer  by  means  of  monitors  as  shown  in  Fig.  71.  The 
sides  of  these  monitors  may  be  fitted  with  swinging  glass  windows, 
with  wooden  or  metal  louvres,  or,  in  case  a  large  amount  of  ventila- 
tion is  required,  may  be  simply  left  open.  Figs.  124, 125,  and  126  give 
details  of  monitors,  and  show  how  they  are  connected  to  the  trusses. 

28.  Gable  Details.    The  gable  is  the  end  of  the  roof  at  that  end 
of  the  building  which  is  parallel  to  the  roof  trusses.    Since  this  extends 
beyond  the  plane  of  the  side  cf  the  building,  some  method  must  be 
employed  in  connecting  the  outer  edge  with  the  wall  of  the  building, 
in  order  to  keep  out  the  rain  and  wind.     Figs.  127  and   128  give 
several  details  which  are  efficient  and  at  the  same  time  economical. 

29.  Cornice  Details.    The  cornice  is  that  edge  of  the  roof  which 
is  perpendicular  to  the  planes  of  the  roof  trusses.     In  addition  to 
being  necessarily  so  constructed  as  to  keep  out  the  wind  and  the 
elements,  it  must  have  in  many  cases  some  form  of  gutter  connected 
to  it,  which  takes  the  water  off  the  roof.    This  gutter  should  be  con- 


216 


ROOF  TRUSSES 


95 


Ridge  Roll  *24  Gage 
-5 paced  every  6  in 


Fig.  133.    Ridge  Koll. 
A'.b'  Yellow  Pine  abt  6 


Flashing 
Steel  5iding 


Fig.  130.    Cornice  Details  for  Steel  Roof. 

See  also  Figs.  129  and  131.  Fig.  134.    Detail  of  Cinder  Flor  r. 

nected  at  intervals  of 
every  three  bays — or,  in 
case  this  exceeds  50  feet, 
every  two  bays — with  a 
pipe  or  conductor  to  carry 
the  water  to  the  ground. 
Gutters,  as  a  general 
thing,  are  semicircular  or 
nearly  so;  and  for  ordi- 
nary spans  they  should 
not  be  less  than  6  inches 
wide.  Conductors  should 
not  be  less  than  5  inches 
in  diameter.  It  is  not 
to  be  supposed  that  the 
water  entirely  fills  either 
the  conductors  or  the 
gutters.  The  sizes  are 
made  so  as  to  allow  for 
any  obstruction  such  as 
dirt  or  ice.  Gutters 
should  preferably  have  a 

pitch  of  one  inch  in  every  10  feet.     Figs.  129  to  131  give  details  of 

cornices  with  various  forms  of  gutters  attached. 

The  ridge,  or  peak  of  the  roof,  is  usually  covered  with  a  plain 

sheet  of  metal,  in  which  case  it  is  called  the  ridge  cap-,  or  with  a 


Fig.  131.    Cornice  Details  for  Steel  Roof.    See  also 
Figs.  129  and  130. 


Fig.  132.    Ridge  Cap. 


217 


96 


ROOF  TRUSSES 


metallic  roll  with  flared  sides,  in  which  case  it  is  called  a  ridge  roll. 

Figs.  132  and  133  show  cross-sections  of  a  ridge  cap  and  a  ridge  roll. 

30.     Floors.    The  floor  of  the  shop  depends  very  largely  upon  the 

purpose  for  which  the  building  is  intended.     It  may  consist  of  earth, 


i"  Rank  T     fZf  Plonk 


'-Tar  or  Asphalt  Concrete.  4-  »)•  Anchor  StakesJ  | 
of  Clean  Grave! .     \JT  V 

Fig.  135.    Detail  of  Asphalt  or  Coal-Tar  Concrete  Floor. 


r  ;'  Wearing  Surface .  I O  Portland  Cement  Morton 


Fig.  136.    Detail  of  Concrete  Floor. 
Channels  abt.  4  ft. centers  r  Concrete 


.'  ^vl p.. :< 


Lonqitudi'nal   Section 


^-Main  Drain  to  Sewer 


Trrmfmm 

Transverse  Section. 


T-  Dolt 
Fig.  137.    Detail  of  Floor  of  Steam  Laboratory  of  the  University  of  Illiu  ^is. 

cinders,  boards,  concrete,  or  sheet  steel.  In  cases  where  men  are 
required  to  work  standing,  cinders  or  boards  give  the  best  results. 
Earth  floors  will  wear  into  holes  in  places  where  the  men  stand,  and 
concrete  or  steel  makes  them  foot-weary  on  account  of  its  inelasticity. 
Where  heavy  machinery  is  installed,  and  men  are  seldom  present 
except  for  a  short  time  at  certain  periods,  concrete  makes  an  ideal 
floor.  Figs.  134,  135,  and  136  show  details  of  various  kinds  of  floors. 
Fig.  137  gives  a  detail  of  the  floor  in  the  Steam  Engineering  Labora- 
tory of  the  University  of  Illinois.  This  consists  of  channels  imbedded 
in  concrete.  These  channels,  which  are  placed  in  pairs  a  small  dis- 
tance apart,  run  both  lengthwise  and  crosswise  of  the  shop.  The 
advantage  of  this  form  of  construction  is  that  machinery  can  be 
placed  anywhere  on  the  shop  floor  and  quickly  bolted  into  place 
by  means  of  T-bolts,  a  detail  of  which  is  shown  in  the  figure. 


218 


H  -B 

O  1 

§  I 

a 


|w  1 4 

w^  I  I 


ill 

SS|1 

Is?  1 


1  ! 


CIVIL   ENGINEERING   SPECIFICA- 
TIONS AND  CONTRACTS 


PAET  I 


INTRODUCTION 

In  the  preparation  for  letting  a  piece  of  work,  the  Engineer 
must,  by  drawing  and  written  description  or  specification,  set 
forth  his  ideas.  He  must  also  make  estimates  of  the  cost  of  the 
work  under  different  methods  of  construction  to  determine  the 
least  expensive  method  of  accomplishing  the  desired  result  and, 
if  he  wishes  to  let  the  work,  he  should  make  such  public  announce- 
ments as  shall  reach  the  greatest  number  of  desirable  contractors. 

In  order  to  insure  an  early  execution  of  the  construction,  it  is 
his  duty  to  prepare  the  form  of  bid  or  proposal,  with  the  instruc- 
tions to  bidders  and,  later,  after  attending  to  the  opening  of  bids, 
he  must  adopt  a  form  of  articles  of  agreement  and  fix  a  bond, 
which,  together  with  the  specifications,  drawings,  and  proposal, 
form  the  contract.  These  various  steps  will  be  treated  in  the 
following  work,  in  the  order  of  their  importance  in  the  contract 
from  the  Engineer's  point  of  view. 

GENERAL  INSTRUCTIONS 

Engineering.  Engineering  may  be  defined  as  the  science  or 
art  of  utilizing  the  forces  and  materials  of  Nature  with  the  great- 
est amount  of  economy.  It  has  been  defined  epigrammatically 
as  "the  science  or  art  of  making  a  dollar  go  the  farthest".  Engi- 
neering is  divided  into  Civil  Engineering,  Mechanical  Engineer- 
ing, Electrical  Engineering,  Mining  Engineering,  Hydraulic  En- 
gineering, Gas  Engineering,  Chemical  Engineering,  Agricultural 
Engineering,  etc.  According  to  modern  usage,  Civil  Engineer- 
ing is  confined  strictly  to  fixed  construction,  such  as  railways, 


2  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

bridges,  docks,  tunnels,  sewers,   aqueducts,   canals,   lighthouses, 
dams,  breakwaters,  etc. 

The  Engineer.  It  is  necessary  that  the  two  parties  to  a  con- 
tract for  the  execution  of  any  important  construction  work  have 
some  one  in  authority  to  decide  all  questions  in  dispute  between 
them,  and  to  see  that  the  work  is  carried  out  in  accordance  with 
the  requirements  of  the  contract.  This  person  is  generally  the 
Engineer  who  designs  the  work,  although  in  some  States,  unless 
the  Engineer's  name  is  written  in  the  articles  of  agreement,  his 
decisions  are  not  binding. 

It  is  his  duty  to  take  a  perfectly  neutral  position  between  the 
two  parties,  and  to  see  that  the  work  is  carried  out  in  strict 
accordance  with  the  contract.  He  should  work  in  harmony  with 
the  contractors,  give  all  possible  aid  to  accelerating  the  work, 
and  take  pains  to  secure  work  and  material  strictly  up  to  the 
standard  of  requirements  in  the  specifications.  Although  he  is 
usually  in  the  employ  of  the  party  for  whom  the  work  is  being 
done,  as  the  arbitrator  his  decisions  must  show  perfect  impar- 
tiality, so  that  both  parties  will  admit  their  justice ;  but  in  order 
that  there  may  be  few  questions  at  issue  between  the  parties  to 
the  contract,  the  Engineer  must  be  thoroughly  familiar  with  tin- 
character  of  the  work  he  is  designing  and  the  quality  of  the 
materials  entering  into  it. 

Contract.  A  contract  is  a  written  or  verbal  agreement  be- 
tween two  or  more  parties  specifying  terms,  conditions,  etc., 
under  which  certain  obligations  are  to  be  discharged.  A  contract 
for  engineering  work  generally  consists  of  the  Advertisement, 
the  Proposal  (including  the  notice  to  bidders),  the  Drawings,  the 
Specifications,  the  Articles  of  Agreement  (generally  spoken  of 
as  the  contract),  and  the  Bond,  which  is  usually  required  to  insure 
the  carrying  out  of  the  contract. 

It  is  the  Engineer's  duty  to  see  that  he  obtains  the  greatest 
amount  of  the  best  work  for  the  least  expenditure  of  money. 
Experience  has  shown  that  to  accomplish  this  end  he  should  first 
determine  the  exact  character  of  the  structure  which  is  to  be 
built  and,  in  addition  to  the  drawings,  which  are  generally  neces- 
sary, he  should  prepare  the  following:  (1)  The  form  of  Speci- 
fication; (2)  the  Agreement;  (3)  the  Proposal,  or  form  of  bid, 


222 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  3 

including  the  notice  to  bidders;  (4)  the  Advertisement.  They 
are  given  above  in  the  order  of  their  importance  to  the  Engineer 
and  Contractor,  and  in  that  order  they  will  be  treated. 

It  is  essential  that  all  parts  of  the  contract  be  prepared  care- 
fully in  order  to  avoid  misunderstanding.  Many  disputes  are 
avoided  by  requiring  contractors  to  make  their  bids  on  a  regular 
form  of  proposal,  furnished  by  the  party  for  whom  the  work  is 
to  be  done.  In  the  case  of  small  or  unimportant  work,  the  bond 
is  often  omitted.  In  some  cases  drawings  are  not  necessary,  and 
in  many  cases  the  work  to  be  done  is  not  advertised,  as  the  work 
may  not  be  of  sufficient  magnitude  to  warrant  the  expense,  and 
as  many  corporations  keep  a  list  of  the  names  of  contractors  who 
are  regularly  asked  to  bid  on  projected  work.  Of  the  above,  the 
drawings  and  the  specifications  are  the  most  important  to  the 
Engineer  and  the  Contractor,  as  they  are  the  guide  for  both  in 
the  execution  of  the  work  and  are  constantly  in  use  during  con- 
struction; hence,  for  convenience,  the  specifications  and  the 
drawings  are  often  so  prepared  that  they  can  be  readily  detached 
from  the  other  components  of  the  contract. 

Drawings.  Very  few  contracts  for  construction  work  are 
drawn  without  plans  of  some  kind.  They1  should  be  made 
accurately  and  on  a  scale  large  enough  to  show  all  details  con- 
veniently and  clearly.  All  dimensions  and  distances  should  be 
written  carefully  upon  the  parts  of  the  detail  drawings  to  which 
they  refer,  and  all  dimensions  should  be  checked  by  a  second 
draftsman.  The  distance  to  be  embraced  by  the  figures  should 
be  indicated  by  dotted  arrows.  The  drawings  should  be  so 
accurate  and  so  complete  that  there  can  be  no  question  as  to  the 
intention  of  the  designer  even  to  the  smallest  detail.  In  pre- 
paring the  specifications,  the  designer  should  keep  a  memoran- 
dum tablet  on  his  table  and  jot  down  every  thought  that  may 
be  of  service.  The  value  of  a  drawing  depends  upon  its 
accuracy. 

The  sheets  should  be  uniform  in  size,  carefully  lettered  or 
numbered  for  reference,  and  should  be  clearly  and  plainly  titled. 
They  should  also  show  the  scale,  the  date  when  completed,  the 
initials  of  the  draftsman,  and  the  initials  of  the  checking 
draftsman. 


223 


4  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Maps  should  show  a  meridian  and  magnetic  variation,  if  the 
latter  be  known. 

The  Government  prohibits  the  letting  of  a  contract  without 
an  accompanying  plan ;  certain  city  ordinances  and  charters  have 
the  same  prohibition.  The  requiring  of  plans  to  accompany  the 
contract  is  to  assure  the  competing  Contractors  that  they  are 
bidding  on  the  same  basis. 

Contracts  are  frequently  drawn  for  patented  or  special  struc- 
tures, without  plans;  in  such  cases,  the  Contractor  furnishes  a 
working  drawing,  subject  to  the  approval  of  the  Engineer,  after 
the  contract  is  executed.  The  specifications  for  such  work  are 
usually  confined  to  a  general  description  of  the  work  required 
and  a  guarantee  of  results  to  be  obtained  by  the  Contractor, 
without  setting  forth  the  detail  of  construction  or  method. 
Sometimes  plans  are  tendered  by  the  bidders — thus  allowing 
the  Engineer  to  make  comparison  and  choice  of  the  different  ideas 
submitted.  This  method  of  letting  contracts  is  not  recommended, 
but  as  the  various  branches  of  Engineering  become  more  special- 
ized and  as  most  of  the  leading  contracting  firms  have  competent 
engineers  who  are  specialists  in  their  particular  line  of  construc- 
tion, it  becomes  necessary  for  the  busy  Engineer,  with  a  general 
practice,  to  make  use  of  the  specialist  in  order  to  keep  pace  with 
modern  construction  methods. 

Specifications.  The  specifications  define  the  exact  relations 
between  the  parties  to  the  contract;  they  are  supplementary  to 
the  drawings  and  should  be  embodied  in  the  contract.  They 
are  a  written  description  of  the  work  to  be  performed  and  should 
show  specifically  whatever  features  are  not  shown  on  the  draw- 
ings. They  should  define  the  quality  and  quantity  of  materials; 
the  methods  of  construction;  the  nature  of  the  workmanship; 
the  manner  of  conducting  the  work;  and  the  general  conditions 
and  stipulations. 

The  specifications  must  be  most  carefully  drawn,  leaving 
nothing  to  the  imagination,  as  they  are  the  guide  to  both 
Engineer  and  Contractor  throughout  the  execution  of  the  work. 
Great  care  must  be  taken  that  no  important  special  and  general 
clauses  be  omitted.  They  should  set  forth  clearly  and  with  great 
exactness  what  is  to  be  done. 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  5 

The  Contractor  is  supposed  to  be  experienced  in  the  special 
class  of  construction  to  be  undertaken,  and  should  not  be  dictated 
to  as  to  methods — except  in  very  special  cases — and  he  should 
be  held  strictly  responsible  for  results.  In  some  cases  the 
Engineer  may  desire  a  specially  manufactured  article  or  material, 
or  a  special  method  to  be  used  in  accomplishing  a  certain  result ; 
in  which  case  it  is  necessary  to  incorporate  the  specifically- 
mentioned  article  and  the  method  of  doing  the  work  in  the  speci- 
fication. If  the  specified  article  is  inherently  unsuitable  for  the 
purpose  intended,  or  the  method  required  does  not  accomplish 
the  desired  result,  the  Contractor  must  not  be  held  for  the 
results,  as  he  is  not  free  to  act  according  to  his  own  ideas  and 
cannot  be  responsible  for  the  mistakes  of  the  Engineer.  Either 
leave  the  methods  and  means  entirely  to  the  Contractor  who  is 
held  responsible  for  results,  or  let  the  Engineer  assume  entire 
charge  of  methods  and  means  and  state  that  the  Contractor  will 
not  be  held  responsible  for  results.  To  attempt  to  follow  both 
courses  at  the  same  time  is  inequitable  and  will  be  so  found  if 
carried  into  the  courts  of  law.  In  plain  words,  the  specifications 
should  point  rather  to  the  finished  structure  than  to  the  method 
of  accomplishing  the  work. 

General  and  Specific  Clauses  or  Provisions.  Specifications  are 
usually  divided  into  general  and  special  clauses  or  provisions. 
The  general  clauses  are  those  that  are  applicable  with  slight 
variations  to  almost  any  important  piece  of  construction  work, 
while  the  special  clauses  refer  to  the  character  of  the  material, 
the  details  of  construction,  the  special  features  and  ideas  to  be 
incorporated,  and  no  details  should  be  spared  that  would  add  to 
the  clearness  of  description  in  every  step  of  the  proposed  work. 
All  clauses  should  be  numbered  and  properly  headed,  preferably 
by  a  marginal  note,  for  convenience  of  reference.  The  general 
clauses  should  be  segregated  from  those  of  a  specific  nature, 
thereby  avoiding  errors  of  omission. 

General  clauses  or  provisions  describe  the  general  relation  of 
the  parties  involved,  the  time  for  beginning  and  completing  the 
contract,  payment  for  the  work,  the  Contractor's  liability,  the 
special  duties  of  the  Contractor,  inspection,  change  of  plans, 
interpretation  of  plans,  measurements,  conduct  of  the  work, 


225 


6  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

maintenance  of  completed  work,  etc.  It  is  advisable  for  the  Engi- 
neer to  have  a  list  of  the  general  conditions  which  are  applicable 
to  most  contracts  before  him  and,  upon  completion  of  the  rough 
copy,  to  check  over  the  clauses  to  see  that  all  the  conditions 
have  been  included.  The  writer  has  a  list  of  over  one  hundred 
headings  that  he  endeavors  to  embody  in  every  specification 
drawn;  although  it  is  not  necessary  to  have  a  special  clause  for 
each  heading,  he  has  found  that  this  is  the  surest  method  to 
prevent  omissions  of  necessary  clauses. 

Great  care  must  be  taken  that  clauses  do  not  contradict  each 
other;  that  they  be  not  at  variance  with  the  plans;  and  that 
ambiguous  description  is  not  introduced. 

Clearness  of  Statement.  The  wise  and  careful  Contractor  will 
note  every  detailed  provision  of  a  specification,  and  will  bid 
accordingly,  expecting  to  do  no  more  than  is  required  in  the 
contract.  Hence  it  is  necessary  that  the  Engineer  set  forth  every 
detail  fully,  clearly,  and  concisely.  "Work  should  be  so  designed 
and  described  as  to  require  no  alteration  in  the  course  of  con- 
struction. 

The  specification  requiring  the  Contractor  to  ask  the  Engineer 
for  an  explanation  of  its  meaning  is  not  clearly  drawn.  The 
Engineer  must  not  suppose  that  the  Contractor  will  take  any- 
thing for  granted;  he  must  draw  his  specification  in  such  a 
manner  as  to  cover  the  work,  in  general  and  in  particular,  in 
every  detail. 

It  is  of  the  greatest  importance  that  there  be  no  ambiguity 
and  no  omission  of  words.  The  clauses  should  be  couched  in  the 
simplest  language  and  the  sentences  should  be  short  and  to  the 
point.  Bad  English,  careless  punctuation,  and  verbosity  are  to 
be  carefully  avoided.  The  incorrect  placing  of  a  comma  has 
caused  the  loss  of  many  thousands  of  dollars.  Write  so  clearly 
that  there  will  be  no  occasion  to  take  the  specification  to  court 
to  decide  what  is  the  "spirit"  of  the  contract;  that  is,  what  was 
intended  by  the  writer  of  the  contract  and  what  the  parties  to  it 
should  understand  by  it.  Repeat  words  or  sentences,  if  it  is  found 
that  the  meaning  is  thereby  made  clearer. 

Precision.  "While  it  is  not  always  possible  to  prescribe  exact 
quantities,  the  word  "about"  is  to  be  avoided  in  specification 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  7 

writing.  Be  precise  in  all  descriptions;  ask  for  nothing  that  you 
do  not  know  to  be  practicable,  and  be  definite  and  specific  in 
every  detail.  The  units  of  measurement  to  be  employed  should 
always  be  clearly  stated. 

Knowledge  Required  of  Engineer.  The  Engineer  must  have  a 
thorough  knowledge  of  every  detail  of  the  work  before  he 
attempts  to  describe  what  the  Contractor  is  to  accomplish  under 
the  specification ;  even  when  understood  perfectly  by  the  Engineer, 
it  is  often  very  difficult  to  describe  exact  requirements. 

Avoidance  of  Unusual  Conditions.  Specifications  should  be  so 
drawn  that  the  best  class  of  material  and  workmanship  consistent 
with  the  amount  of  money  to  be  expended  on  the  undertaking 
be  obtained.  Avoid  conditions  which  are  unusual  and  beyond 
the  ordinary  requirements  of  good  practice,  and  which  are  not 
absolutely  necessary  to  the  results  desired.  The  Contractor  will 
generally  bid  a  figure  out  of  all  reasonable  proportion,  to  insure 
himself  against  loss  on  work  of  a  character  with  which  he  is 
entirely  unfamiliar.  Remember  that  Engineering  has  been 
defined  as  "the  science  or  art  of  making  a  dollar  go  the  farthest". 
Many  young  engineers  are  prone  to  introduce  into  their  work 
some  new  idea  of  their  own,  of  doubtful  utility,  for  the  sake  of 
novelty  and  self-advertisement,  where  a  more  conservative  man 
will  follow  the  beaten  road  of  approved  practice. 

Materials  Employed.  The  materials  of  construction  should,  to 
as  great  an  extent  as  possible,  be  those  readily  found  in  the  local 
markets  and  in  the  neighborhood  of  the  work.  This  does  not 
mean,  however,  that  any  inferior  or  unsuitable  material  may  be 
allowed  to  enter  into  the  work ;  on  the  contrary,  the  most 
approved  practice  should  be  required  both  as  to  materials  and 
workmanship.  The  Engineer  may  be  sure  that  he  will  not  get  a 
better  quality  of  material  than  that  specified,  and  will  often  get  a 
poorer  one.  Be  careful  in  regard  to  specifying  materials  of  special 
manufacture,  as  the  Engineer  must  be  above  the  suspicion  of 
favoring  any  particular  make  or  brand.  It  is  wise  to  set  as  a 
standard  the  best  brand  on  the  market  and  then  require  it,  or 
its  equal.  It  is  generally  best  to  set  forth  the  requirements  or 
tests  that  a  material  must  fulfill,  in  preference  to  naming  the 
special  manufacture. 


227 


8  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Extra  and  Additional  Work.  "What  constitutes  extra  and  addi- 
tional work  is  the  most  frequent  cause  of  controversy  between  the 
Engineer  and  the  Contractor;  therefore,  the  greatest  care  should 
be  used  in  specifying  what  should  constitute  each.  Extra  work 
may  be  defined  as  work  entirely  unforeseen  at  the  time  of  the 
drawing  of  the  contract;  while  additional  work  is  work  of  the 
same  quality  and  workmanship  as  that  described  in  the  specifica- 
tion, which  can  be  foreseen  but  not  accurately  calculated.  The 
proposal  should  include  unit  prices  for  the  various  items  of 
materials  and  workmanship,  which  it  is  thought  may  be  required 
to  complete  the  construction,  over  and  above  the  work  described 
in  the  specifications,  in  order  that  there  be  no  cause  for  contro- 
versy over  the  items  of  additional  work.  But  where  there  have 
been  omissions  in  the  requirements  of  the  specifications;  when 
alterations,  changes,  and  additions  become  necessary;  where 
errors  have  been  made  in  lines  or  grades ;  where  new  methods  or 
materials  are  experimented  with  by  the  Engineer ;  where  damaged 
work  is  replaced;  or  where  the  work  has  to  be  extended  to 
secure  greater  strength,  durability,  or  stability,  there  is  fre- 
quently more  or  less  controversy  as  to  just  what  shall  constitute 
extra  work  under  the  contract.  This  trouble  can  be  avoided  by 
defining  clearly  just  what  work  is  to  be  done  by  the  Contractor, 
and  by  requiring  nothing  of  him  beyond  the  lines  of  the  work  so 
defined. 

Dividing  Line  between  Contracts.  The  dividing  line  between 
contracts  should  be  very  carefully  described  and,  where  there 
are  several  contractors  on  one  piece  of  work,  the  exact  limits  of 
the  work  to  be  performed  by  each  one  must  be  set  forth  most 
carefully. 

The  work  for  each  of  the  several  contractors  should  be 
described  under  separate  headings,  care  being  taken  that  each 
contractor  agree  to  leave  his  work  in  such  condition  as  to  work 
no  hardship  on  the  one  following  him. 

Verbal  Information  to  Contractor.  A  clause  in  the  specifica- 
tion should  state  that  any  information,  whether  verbal  or  other- 
wise, secured  by  the  Contractor  from  the  Engineer  or  his  assist- 
ants prior  to  the  signing  of  the  contract  is  not  binding,  and  that 
only  the  information  as  shown  on  the  plans,  or  set  forth  in  the 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  9 

specifications,  has  bearing  on  the  contract.  The  specification  is, 
and  should  be  stated  therein  to  be,  a  part  of  the  contract.  The 
plans  and  specifications  should  give  as  full  information  as  possible 
as  to  conditions  and  difficulties  that  may  be  met  with,  such  as 
soundings,  borings,  character  of  material,  amount  of  water  to  be 
encountered,  etc. ;  and  any  special  difficulties  known  to  the 
Engineer  should  be  noted  in  the  specification,  and  no  information 
of  use  to  the  Contractor  in  making  up  his  bid  should  be  omitted. 
Mistakes  in  Plans  and  Specifications.  Finally,  every  precau- 
tion must  be  taken  to  prevent  mistakes  in  the  plans,  and  omissions 
or  conflicting  clauses  in  the  specifications.  Every  possible  check 
against  errors  should  be  made  use  of.  When  errors  are  discov- 
ered in  the  course  of  the  work,  no  time  should  be  lost  in  admitting 
them  and  setting  about  to  rectify  them.  The  principal  object  is 
to  produce  a  finished  piece  of  work,  constructed  according  to 
the  best  approved  practice,  that  will  be  a  credit  to  the  Engineer, 
as  well  as  to  every  one  who  has  had  a  hand  in  its  construction. 

GENERAL  PROVISIONS 

DETAILS  PRIOR  TO  BEGINNING  WORK 

Grouping  Provisions.  There  is  a  great  difference  of  opinion 
as  to  the  proper  location  of  certain  general  provisions  in  con- 
tracts. Some  place  them  in  the  articles  of  agreement,  while 
others  place  the  same  clauses  in  the  specification.  The  writer 
advises  keeping  the  general  clauses  together  as  much  as  pos- 
sible, grouping  them  so  as  to  indicate  their  character  and 
placing  them  almost  entirely  in  the  specification,  making  the 
contract  as  short  and  concise  as  possible.  The  proper  grouping 
is  very  difficult,  as  many  of  the  clauses  might  be  placed  in  any  of 
several  groups. 

In  drawing  up  specifications  it  is  a  good  practice  for  the 
Engineer  to  keep  before  him  a  list  of  general  provisions  covering 
all  cases  and,  while  all  the  provisions  will  not  apply  to  any  one 
contract,  this  will  be  a  great  aid  in  preventing  omissions.  Some 
of  the  following  apply  to  one  class  of  work  only  and  have  been 
grouped  under  the  various  headings,  all  being  written  as  though 
one  of  the  parties  to  the  contract  was  the  "Company",  the  other 
the  "Contractor".  Of  course,  the  wording  would  be  modified 


10  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

in  case  the  work  were   being   done   for   a  municipality   or   an 
individual. 

Careful  Statement  of  Definitions.  To  prevent  disputes,  the 
principal  parties  to  the  contract  and  their  representatives  should 
be  clearly  defined;  hence  the  necessity  of  a  clause  of  the  following 
character  in  most  specifications : 

Definitions.  The  following  words  and  expressions  used  in  this 
contract  shall  be  defined  and  construed  as  follows : 

City:     The  City  of 1 

Director:     The  Director  of  the  Department  of  Public  Works  of 

the  City  of 

Chief  Engineer :     The  person  holding  the  position  or  acting  in 

the  capacity  of  the  Chief  Engineer  of  the - 

Company. 

Engineer:     The  Chief  Engineer  of  the Company, 

or,  in  his  absence,  his  regularly  appointed  and  authorized 
Assistant  Engineer,  and  Inspectors  representing  him, 
limited  to  the  special  duties  intrusted  to  them  and  to  no 

other  employe  of  the Company. 

Contractor :  The  individual,  parties,  firm,  or  corporation  with 
whom  or  with  which  the  contract  is  made,  or  an  author- 
ized agent  thereof. 

Other  words  often  have  to  be  defined,  such  as  Owner,  Pur- 
chaser, Trustee,  Board,  Directors,  President,  Treasurer,  each  of 
which  should  be  clearly  defined  so  that  there  can  be  no  possible 
question  as  to  its  precise  use. 

DRAWINGS,  PLANS,  ETC. 

The  following  group  of  clauses  relate  to  drawings,  or  plans, 
and  notes  on  them : 

Construing  Specifications  and  Plans.  To  avoid  disputes  and 
litigation,  it  must  be  distinctly  understood  by  the  Contractor 
that  the  Engineer  of  the  Company  shall  construe  the  specifica- 
tions and  approved  plans;  and  explain  any  obscurity  therein;  and 
shall  have  the  right  to  correct  any  errors  or  omissions  in  either 
and  decide  as  to  their  purpose  and  intent ;  and  his  decision  upon 
any  doubtful  or  disputed  point  shall  be  final,  conclusive,  and 
binding  upon  the  Company  and  the  Contractor.  The  action  of 
such  correction  shall  be  in  force  from  the  time  the  Engineer 
gives  due  notice  thereof  in  writing. 


?30 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  11 

Plans  and  Specifications  of  Equal  Force.  The  approved  plans 
and  the  specifications  shall  be  of  equal  force  and  effect  and,  in 
case  of  discrepancy  between  the  plans  and  the  specifications,  or 
between  the  plans  and  the  details,  or  any  lack  of  agreement  in 
measurements  upon  different  plans,  or  different  figures  upon  the 
same  plan,  they  must  be  submitted  to  the  Engineer  for  interpreta- 
tion before  beginning  construction  of  the  work.  Dimensions 
shown  in  figures  on  the  plans  shall  have  preference  over  the  scale. 

General  Drawings.  The  Company  will  furnish  to  bidders 
drawings  giving  all  general  dimensions  and  sizes,  and  such  par- 
tially detailed  drawings  as  may  be  required  to  cover  special 
features.  After  assigning  the  contract,  such  other  drawings  as 
may,  in  the  judgment  of  the  Engineer,  be  required,  will  be  fur- 
nished by  the  Company.  The  Contractor  shall  prepare  drawings 
for  shop  work,  which  shall  include  all  details  required  to  supple- 
ment and  complete  the  general  and  partially  detailed  drawings 
furnished  by  the  Company;  and  he  shall  submit  3  blueprints 
of  each  sheet  for  the  approval  of  the  Engineer.  After  approval, 
if  required,  additional  prints  shall  be  furnished.  The  approval 
of  the  Engineer  shall  in  no  way  relieve  the  Contractor  from 
responsibility  for  the  correctness  of  all  detail  drawings  before 
going  to  the  shop,  nor  for  the  accurate  and  complete  execution 
of  the  work. 

Work  in  Accordance  with  Plans.  The  work  and  all  its  appur- 
tenances shall  be  built  of  material,  size,  and  dimensions,  on  the 
lines,  to  the  depths,  and  in  the  manner  shown  on  the  plans  filed 
in  the  office  of  the  Company.  No  deviation  from  them  will  be 
allowed  unless  by  permission  in  writing  from  the  Engineer. 

Record  Drawings.  The  Contractor,  upon  completion  of  the 
work,  shall  furnish  3  complete  sets  of  blueprints  on  linaura,  of 
detail  drawings  of  the  machinery  and  all  appurtenances;  each 
set  shall  be  neatly  bound  in  cloth  for  record  drawings  of  the 
work  embraced  under  the  contract  as  a  whole. 

Plans  and  Specifications.  The  approved  plans  and  a  copy  of 
the  specifications  are  to  be  kept  constantly  at  the  work  by  the 
Contractor  or  his  authorized  foreman. 

Necessary  to  Render  the  Work  Complete.  If  any  workman- 
ship or  materials  be  required,  which  are  obviously  necessary  to 
carry  out  the  full  intent  and  meaning  of  the  plans,  details,  dia- 
grams, and  specifications,  although  the  same  may  not  be  either 
directly  or  indirectly  so  specifically  noted  by  drawings  or  speci- 
fications, the  Contractor  is  hereby  bound  to  consider  and  provide 
for  the  same  in  his  proposal  for  the  work,  as  fully  as  if  they 
were  so  specifically  denoted,  and  shall  execute  the  same  without 
charge  or  claim  therefor. 


231 


12  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Notes  upon  Drawings.  Contractors  proposing  for  any  of  the 
work  under  these  specifications  will  be  expected  to  examine  all 
the  notes  upon  the  plans,  which  are  intended  to  form  a  part  of 
the  specification.  No  consideration  fwill  be  given  to  any  claim 
that  these  notes  have  been  overlooked. 

Verbal  Agreements.  This  contract  shall  in  no  wise  be  affected 
by  verbal  agreements  or  inferences  from  conversations  previous 
to  or  subsequent  to  its  execution. 

MEASUREMENTS,  LINES,  AND  GRADES 

The  following  paragraphs  may  be  grouped  under  Measure- 
ments, Lines,  and  Grades: 

Lines  and  Grades  by  Engineer.  The  work  shall  be  laid  out  on 
the  ground  by  the  Engineer,  who  shall  direct  the  lines  and  grades 
that  are  to  be  observed,  and  all  marks  given  by  him  shall  be  care- 
fully preserved  by  the  Contractor,  who  shall  provide  such  stakes, 
forms,  and  assistance  in  doing  the  work  as  may  be  demanded 
of  him  by  the  Engineer. 

Marks  and  Stakes  to  be  Preserved.  Contractors  must  care- 
fully preserve  bench  marks  and  stakes  and,  in  case  of  willful  or 
careless  neglect,  they  shall  be  charged  whatever  the  Engineer 
shall  consider  an  equitable  amount  to  cover  damages  arising 
from  such  negligence,  the  same  to  be  deducted  from  the  amount 
due  upon  the  completion  of  the  work. 

Work  to  Conform  to  Lines,  etc.  All  construction  work  shall 
conform  to  the  lines  and  stakes  set  out  by  the  Engineer,  and  any 
increase  of  labor  or  material  required,  due  to  the  neglect  of  these 
lines  and  stakes,  shall  not  be  estimated  or  paid  for. 

Standard  of  Measure.  All  measurements  are  given  on  the 
plans  and  shall  be  measured  in  United  States  standard  feet. 
Where  vertical  dimensions  are  preceded  by  the  sign  -f-  or  — , 
they  refer  respectively  to  above  or  below  an  established  hori- 
zontal plane  called  datum,  which  is feet  above  (or  below) 

mean  high  water  and feet  above  (or  below)  the  mean  low 

water  in  the at 

Measurements.  All  quantities  shall  be  determined  by  measure- 
ments in  United  States  standard  feet,  made  to  the  prescribed 
lines.  No  work  outside  these  lines  shall  be  paid  for.  No  con- 
structive conventional  measurement  will  be  allowed,  any  rule  or 
custom  in  the  section  of  the  country  through  which  the  road 
passes,  to  the  contrary  notwithstanding. 

Quantity  Estimates.  It  is  distinctly  understood  by  both 
parties  to  a  contract,  that  the  quantities  of  material  of  all  kinds 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  13 

shown  on  the  plans  or  in  the  specifications  are  merely  approxi 
mate,  and  will  not  in  any  manner  affect  the  final  settlement 
because  of  the  fact  that  at  the  time  of  drawing  up  the  specifica- 
tions it  was  impossible  to  determine  them  accurately. 

The  Company  reserves  the  right  to  require  the  use  of  what- 
ever materials  may  be  necessary  for  the  safe  and  efficient  tem- 
porary and  permanent  construction  of  the  work;  also  the  right 
to  increase  or  diminish  the  quantities  to  the  extent  found  neces- 
sary by  the  Engineer. 

FULFILLING  THE  CONTRACT 
EXECUTION  OF  WORK 

The  following  clauses  are  generally  grouped  under  Execution 
of  the  Work: 

Prosecution  of  Work.  The  Contractor  shall  commence,  prose- 
cute, and  complete  the  work  in  all  its  parts  in  the  most  energetic 
and  workmanlike  manner,  and  shall  prosecute  the  work  at  and 
from  as  many  different  points,  at  such  times,  in  such  parts,  and 
with  such  force  of  workmen,  as  the  Engineer  during  the  progress 
of  the  work  may  determine. 

Should  the  necessary  land  or  right  of  way  not  be  procured 
at  any  place  when  the  Contractor  desires  to  work  thereon,  he 
shall  distribute  his  forces  to  such  other  points  as  may  be  desig- 
nated by  the  Engineer,  without  any  claim  for  damages  for  failure 
to  procure  such  land  or  right  of  way. 

Delay  in  Procuring  Right  of  Way  or  Land.  The  Company 
shall  procure  the  necessary  right  of  way  and  lands  needed  for 
the  work  to  be  done  under  this  contract;  but  it  is  agreed  and 
understood  that,  until  the  said  Company  shall  have  procured  all 
the  right  of  way  or  land  required  for  this 'contract,  the  Contractor 
shall  commence  work,  or  make  arrangements  for  commencing 
work,  entirely  on  such  ground  as  the  Engineer  may  designate. 
The  Contractor  shall  not  have  any  claim  for  damage  or  detention 
by  reason  of  delay  in  procuring  titles  to  lands,  but  he  shall  be 
entitled  to  an  extension  of  time  on  each  part  of  the  work  on 
which  he  was  prepared  to  commence,  equal  to  the  time  lost  from 
and  after  the  day  when  he  was  so  prepared,  provided  such  deten- 
tion shall  exceed  10  days.  In  all  such  cases,  however,  the  Con- 
tractor shall  notify  the  Engineer  in  writing  when  and  where  he 
desires  to  commence  work. 

Duties  of  Contractors.  Contractors  will  be  required  to  give 
their  personal  attention  and  supervision  to  the  work  and  will 
not  be  allowed  to  sublet  the  whole  or  any  part  of  the  same  with- 


233 


14  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

out  the  consent  of  the  Company  having  been  given  thereto  in 
writing. 

Contractors  must  satisfy  themselves  by  a  careful  personal 
examination  of  the  nature  and  location  of  the  work  fpr  which 
they  bid,  of  the  general  form  of  the  surface  of  the  ground,  and 
all  other  matters  which  can  in  any  way  influence  their  contracts ; 
and  no  information  upon  such  matters  derived  from  maps,  plans, 
profiles,  drawings,  or  specifications,  or  from  the  Engineer  or  his 
Assistants,  shall  in  any  way  relieve  the  Contractor  from  any 
risk,  or  from  fulfilling  any  of  the  terms  of  this  agreement. 

Borings.  The  Company  does  not  guarantee  the  correctness 
of  the  borings  nor  the  nature  of  the  materials  shown  upon  the 
plans.  The  Contractor  must  assume  all  risks  resulting  from  any 
differences  from  the  borings  found  to  exist  when  the  construction 
is  under  way. 

All  loss  or  damage  arising  from  any  unforeseen  obstructions 
or  difficulties  encountered  in  the  prosecution  of  the  work  shall  be 
sustained  by  the  Contractor.  The  soundings  and  borings,  and 
the  profiles  based  thereon,  are  to  be  taken  merely  as  guides  for 
the  Contractor  in  bidding,  and  must  not  be  construed  to  relieve 
him  from  responsibility  in  determining  for  himself  the  nature 
of  the  materials  which  will  be  encountered. 

Care  of  Materials.  The  Contractor  shall  receive,  care  for, 
and  be  responsible  for  all  materials  purchased  by  the  Company 
and  delivered  to  the  said  Contractor  at  the  point  herein  desig- 
nated. In  case  of  loss  by  fire,  flood,  breakage,  theft,  carelessness, 
etc.,  the  Contractor  shall  make  good  any  loss. 

NOTE. — This  clause  is  necessary  when  the  Company  is  supplying  part  or 
all  of  the  materials  of  construction,  such  as  spikes,  bolts,  etc.,  in  track-laying 
contracts;  lumber  or  iron  in  bridge  work,  when  the  contract  is  for  the 
erection  of  the  material  only,  and  parallel  cases. 

Materials  to  be  Furnished.  The  Contractor  shall  furnish  all 
materials  required,  which  shall  be  in  full  accordance  with  these 
specifications  and  the  general  and  detail  drawings,  as  they  may 
be  approved  by  the  Engineer,  and  shall  also  furnish  all  labor, 
tools,  and  machinery  necessary  and  all  must  be  of  the  kind 
best  adapted  to  the  efficient,  prompt,  and  safe  execution  of  the 
work. 

Right  of  the  Company  to  Employ  Additional  Men.  If  at  any 
time,  in  the  judgment  of  the  Engineer,  the  Contractor  shall 
neglect  to  prosecute  the  work  with  a  force  sufficient  for  its  com- 
pletion within  the  time  specified,  the  Company  may  employ  such 
number  of  working  laborers  and  foremen  as,  in  its  opinion,  may 
be  necessary  to  insure  the  completion  of  the  work  within  the 


234 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  15 

time  specified  in  the  contract,  at  such  wages  as  it  may  find  neces- 
sary or  expedient;  and  may  pay  all  persons  so  employed,  and 
charge  all  amounts  so  paid  as  so  much  money  paid  to  the  Con- 
tractor under  this  contract. 

Extension  of  Time.  If  the  Contractor  shall  not  complete  the 
work  within  the  time  specified  in  the  contract,  and  the  Company 
shall,  notwithstanding  such  failure,  permit  the  Contractor  to 
proceed  with  or  complete  the  work  as  if  such  time  had  not 
elapsed,  such  permission  shall  not  be  deemed  a  waiver  in  any 
respect  by  the  Contractor  of  any  forfeiture  or  liability  for  dam- 
ages or  expense  thereby  incurred,  arising  from  such  noneomple- 
tion  of  the  work  within  the  time  specified  and  covered  by  the 
"Liquidated  Damages"  clause  of  this  contract;  but  such  for- 
feiture or  liability  shall  still  continue  in  full  force  against  the 
Contractor  as  if  such  permission  had  not  been  granted. 

NOTE. — Where  no  time  for  completion  of  the  work  is  given,  the  work  must 
be  completed  within  a  reasonable  time. 

Twelve  o'clock  midnight  of  the  day  named  in  the  contract  as  the  date  of 
completion  is  the  limit  of  time  unless  a  certain  hour  has  been  specifically  named. 
Time  clauses  should  state  whether  Sundays  and  holidays  are  excluded  from  the 
specified  period. 

What  Prices  are  to  Include.  The  prices  specified  in  the 
accepted  proposal  and  contract  shall  include  the  supply  and 
erection,  in  a  good,  sound,  substantial  and  workmanlike  manner, 
of  all  dams,  flumes,  pilings,  shorings,  sheathing,  shafts,  forms, 
centering,  false  works,  tramways,  machinery,  and  scaffolding; 
also  pumping,  labor,  workmanship,  tools,  fuel,  and  materials 
necessary  for  both  permanent  and  temporary  works,  including 
all  the  items  herein  mentioned  (unless  specifically  stated  other- 
wise) for  the  prompt  completion  of  the  whole  work  proposed  for, 
shown  on  the  drawings,  and  described  in  these  specifications. 
All  materials  and  workmanship  shall  be  of  the  best  quality 
and  description,  and  the  work  perfect  and  complete  in  all  its 
parts. 

NOTE. — This  provision  will  change,  as  to  the  different  items  included, 
depending  on  the  character  of  the  work;  for  while  the  clause  is  applicable  to 
a  sewer,  or  pipe-laying  contract,  it  would  not  cover  the  requirements  for 
track  laying. 

INSPECTION  OF  WORK 

The  following  four  clauses  are  grouped  under  Inspection: 

Inspection  During  Construction.  The  Contractor  shall  at  all 
times  afford  every  facility  for  inspecting  materials  and  workman- 
ship. Any  materials  or  workmanship  not  in  accordance  with 


235 


16  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

the  plans  and  specifications  shall  be  replaced  with  approved 
material  or  workmanship,  or  both,  within  the  time  fixed  by  the 
Engineer;  and  all  rejected  materials  shall  be  immediately  and 
entirely  removed  from  the  site  of  the  work.  If,  after  written 
notice  to  the  Contractor,  the  rejected  materials  are  not  removed 
or  the  condemned  work  built  anew  within  the  time  fixed,  the 
Company  shall  be  at  liberty  to  remove  the  rejected  materials 
and  supply  new  materials,  or  build  anew  any  unapproved  work, 
at  the  expense  of  the  Contractor,  and  the  cost  thereof  shall  be 
deducted  from  any  money  which  may  be  due  him. 

Nothing  in  this  contract  shall  be  construed  as  vesting  in  the 
Contractor  any  right  of  property  in  the  materials  used,  after  they 
have  been  attached  or  affixed  to  the  work  on  the  soil;  but  all 
such  materials  shall,  upon  being  so  attached  or  affixed,  become 
the  property  of  the  Company. 

Materials  and  workmanship  may  be  inspected  at  any  time. 
All  structural  steel  shall  bear  the  Inspector's  mark  of  acceptance. 
The  Contractor  shall  execute  the  work  in  the  presence  of  an 
Inspector  at  all  times;  work  in  absence  of  same  shall  be  subject 
to  rejection. 

Final  Inspection.  The  final  inspection  and  acceptance  of  the 
work  will  take  place  after  construction;  and  any  inspection  and 
acceptance  of  materials  and  workmanship  at  the  site  of  the  work, 
foundries,  shops,  etc.,  to  facilitate  the  progress  of  the  work,  shall 
not  prevent  rejection  of  such  materials  and  workmanship  there- 
after, if  the  same  be  found  unsuitable  or  imperfect. 

Cost  of  Engineering  and  Inspection.  The  cost  of  engineering 
and  inspection,  after  the  expiration  of  the  time  agreed  upon  in 
the  contract  for  the  completion  of  the  work,  shall  be  at  the 
expense  of  the  Contractor,  and  such  cost  shall  be  deducted 
from  the  amount  due  the  Contractor  at  the  time  for  final 
payment. 

Labor  Furnished  to  Inspector.  If  required,  the  Contractor 
shall  furnish  such  labor  as  the.  Engineer  shall  deem  necessary  to 
assist  in  the  inspection  of  materials  to  be  embodied  in  the  con- 
struction under  this  contract  and  to  assist  in  giving  lines  and 
grades  on  the  work,  all  free  of  cost  to  the  Company. 

NOTE. — This  provision  is  unusual  and  is  used  or  enforced  only  in  com- 
paratively small  contracts,  or  when  it  would  be  unjust  to  expect  the  Company 
to  keep  a  corps  of  engineers  and  inspectors  on  work  indefinitely  to  accommo- 
date a  Contractor  who  is  in  default  with  his  work.  On  small  contracts, 
requiring  little  or  only  occasional  staking  out,  or  where  the  work  is  in  remote 
sections,  it  is  customary  to  get  the  assistance  of  some  of  the  Contractor's 
laborers  to  drive  the  stakes,  cut  brush,  etc,,  to  avoid  the  expense  of  maintaining 
a  large  corps  constantly  on  the  work. 


236 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  17 

PROTECTIVE  AND  LABOR  CLAUSES 

Builders'  Insurance.  The  Contractor  will  be  required  to  take 
out  from  time  to  time,  in  an  approved  company,  a  Builders' 
Insurance  Policy  covering  the  value  of  all  materials  liable  to  in- 
jury by  fire,  incorporated  in  or  brought  to  the  work,  and  shall 
assign  same  to  the  Company.  The  policy  shall  be  approved  as  to 
form  and  amount  by  the  Engineer. 

Freezing  Weather.  The  work  shall  be  carried  on  in  cold 
weather  only  at  such  times  and  in  such  manner  as  directed  by 
the  Engineer.  "When  work  is  done  during  freezing  weather,  if 
required,  the  Contractor  shall  provide  proper  facilities  for  heat- 
ing the  materials  entering  into  the  work  and  shall  thoroughly 
protect  the  new  construction  from  damage  caused  by  the 
elements,  during  and  after  building.  Upon  the  suspension  of 
work  due  to  freezing  weather,  all  new  work  shall  be  protected 
and  the  grounds  left  in  good  order. 

Competent  Men  and  Discharge  for  Cause.  The  Contractor 
shall  employ  only  competent  men;  and  he  shall  discharge  any 
foreman  or  other  employe  who  shall,  in  the  judgment  of  the 
Engineer,  be  unfaithful,  unskillful,  or  remiss  in  the  performance 
of  his  work,  or  guilty  of  riotous,  disrespectful,  or  otherwise 
improper  conduct ;  and  no  person  so  discharged  upon  this  work, 
or  any  other  work  done  for  the  Company,  shall  be  employed 
again  by  the  Contractor  upon  the  work  to  be  done  under  this 
contract  without  the  written  consent  of  the  Engineer.  The  work 
under  this  specification  shall  be  subject  to  all  federal,  state, 
and  (or)  municipal  laws,  or  regulations,  in  regard  to  the  employ- 
ment of  laborers,  workmen,  and  mechanics  and  also  those  laws 
regulating  the  hours  of  employment  of  such  employes;  and  fur- 
ther, before  receiving  each  payment,  the  Contractor,  if  required 
by  the  Engineer,  shall  furnish  an  affidavit  that  such  laws  have 
been  faithfully  fulfilled. 

Employment  of  Labor.  The  Contractor,  in  the  construction 
of  the  work,  shall  give  preference  in  employment  to  citizens  of 
the  commonwealth;  and  in  the  employment  of  mechanics  and 
laborers,  where  citizens  of  the  commonwealth  are  not  available, 
shall  give  preference  to  citizens  of  the  United  States  who  are  not 
citizens  of  the  commonwealth.  Persons  employed  in  the  per- 
formance of  manual  labor  under  this  contract  shall  not  be 

required  to  work  more  than. hours  in  each  day, 

and hours  shall  constitute  a  day's  work.*  The 

Contractor  shall  neither  directly  nor  indirectly  require  as  a  con- 

*  An  8-,  9-,  or  10-hour  day  should  be  specified,  according  to  local  laws  and 
circumstances. 


837 


18  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

dition  of  the  employment  of  any  person  that  the  employe  shall 
lodge,  board,  or  trade  at  a  particular  place  or  with  a  particular 
person,  but  every  employe  shall  lodge,  board,  and  trade  where 
and  with  whom  he  elects. 

Foreign  Corporations.  The  Contractor,  if  a  foreign  corpora- 
tion, shall  file  with  the  Company,  if  so  requested,  duly  authenti- 
cated copies  of  its  charter  or  certificate  of  incorporation. 

NOTE. — It  is  of  the  greatest  importance  that  a  corporation,  attempting 
to  do  business  in  a  State  other  than  that  under  whose  laws  it  was  incorporated, 
secure  a  license  and  certificate  to  do  business  in  said  State  as,  in  many  States, 
without  such  license,  the  corporation  cannot  enforce  jts  claims  in  the  courts. 
As  the  laws  differ  in  every  State,  it>is  advisable  that  the  Engineer  secure  the 
advice  of  a  local  attorney  at  law,  of  good  standing,  to  advise  in  regard  to  the 
legal  provisions  of  the  contract. 

MISCELLANEOUS  OBLIGATIONS  OF  CONTRACTOR 

Orders  and  Instructions.  The  Contractor  must  strictly  follow, 
without  delay,  all  orders  and  instructions  of  the  Engineer  or  his 
authorized  assistant,  in  the  prosecution  and  completion  of  the 
work,  and  every  part  thereof. 

Personal  Attention.  The  Contractor  is  required  to  give  his 
personal  attention  to  the  faithful  prosecution  of  the  work,  and 
not  to  sublet  or  assign  the  same,  without  the  written  consent  of 
the  Company,  but  to  keep  it  under  his  own  control ;  and,  in  case 
of  his  absence,  to  have  a  competent  representative  or  foreman  on 
the  work,  who  shall  receive  orders  and  directions  from  the 
Engineer  and  Inspector  and  have  the  same  Carried  out  without 
delay,  and  who  shall  have  full  authority  to  supply  men,  material, 
and  labor  immediately. 

Time  of  Commencement  and  Completion.  The  Contractor 

shall  begin  work  within days  from  the  date  of  the 

notice  given  to  that  effect  by  the  Engineer,  and  he  shall  complete 
all  the  work  under  this  contract  in  the  time  specified,  which  will 
be  reckoned  from  the  date  of  said  notice. 

Delays.  No  charge  shall  be  made  by  the  Contractor  for 
hindrance  or  delay  from  any  cause  during  the  progress  of  any 
portion  of  the  work  embraced  in  this  contract;  but  such  hin- 
drance or  delay  may  entitle  him  to  an  extension  of  time  allowed 
for  completing  the  work,  sufficient  to  compensate  for  the  deten- 
tion, to  be  determined  by  the  Engineer,  provided  the  Contractor 
shall  give  the  Engineer  immediate  notice,  in  writing,  of  the  cause 
of  the  detention. 

A  contractor  on  any  one  or  more  of  several  sections,  into 
which  the  work  may  be  divided,  will  not  be  allowed  any  claim 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  19 

for  delay  on  account  of  any  act  of  a  contractor  or  contractors 
on  a  neighboring  section  or  sections. 

Use  of  Coal  under  Boilers.  The  Contractor  shall  in  all  cases, 
where  steam  power  is  employed  in  streets,  use  anthracite  coal 
under  the  boilers  for  generating  steam  and,  where  ordered  by 
the  Engineer,  shall  provide  electric  power  for  operating  all 
power-driven  machinery. 

Filling-In  of  Old  Drains.  All  sewers,  culverts,  drains,  or 
basins  met  with  and  rendered  unnecessary,  or  becoming  disused 
by  the  construction  of  the  work  herein  contemplated,  must  be 
filled  in,  and  the  street  or  ground  over  their  site  must  be  restored, 
without  extra  charge. 

Location  of  Underground  Structures.  Where  existing  sewers, 
water  or  gas  mains,  electric  and  other  conduits,  met  with  during 
the  progress  of  the  work,  are  shown  upon  the  plans,  the  locations 
of  the  structures  are  intended  to  be  approximate  only.  The  Com- 
pany will  not  be  responsible  for  any  omission  upon  the  plans  as  to 
the  location  of  such  sewers,  pipes,  or  conduits  met  with  in  exca- 
vation, nor  for  any  errors  in  locations  due  to  incomplete  or  faulty 
records. 

Buildings  for  Engineer  and  Inspector.  The  Contractor  shall 
provide  at  least  120  square  feet  of  floor  space  in  a  suitably  heated, 
satisfactory  building  with  doors,  windows,  locks,  etc.,  near  the 
work,  for  the  use,  when  required,  of  the  Engineer  and  Inspectors 
in  charge  of  the  work.  Telephone  service  shall  be  furnished  by 
the  Contractor  for  the  use  of  the  Engineer  and  Inspectors  in 
charge. 

NOTE. — While  unnecessary  in  some  eases,  it  is  always  advisable  to  have 
a  private  room  for  the  Engineer  or  Inspector  where  plans  and  instruments  may 
be  safely  kept. 

Work  Day  and  Night.  The  work  shall  be  carried  on  day  and 
night,  if  necessary,  to  complete  within  the  time  specified. 

Pipes  and  Electric  Wires.  The  Contractor  shall  take  care  of 
all  pipes  and  electric  wires  encountered  on  the  work,  see  that 
they  are  properly  protected,  that  they  are  raised  and  lowered 
when  necessary,  and  that  they  are  not  injured  in  any  way;  all 
damage  done  to  such  property  shall  be  paid  for  by  the  Contractor. 
He  shall  maintain  the  flow  of  drainage,  whether  on  the  surface 
or  underground.  The  cost  of  all  such  work  shall  be  included  in 
the  price  bid. 

Property  of  Contractor.  Generally,  all  waste  materials  exca- 
vated, or  removed  from  within  the  required  limits  of  the 
excavation,  shall  be  considered  the  property  of  the  Contractor; 


20  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

excepting  private  property,  bridges,  or  parts  thereof,  water  and 
gas  pipes,  which,  in  case  they  are  not  required  to  be  replaced, 
shall  be  removed  to  such  locality  as  may  be  directed  by  the 
Engineer.  The  materials  excavated  shall  be  reserved  for  better 
construction,  support,  and  protection  of  the  work  when  required. 

When  the  work  under  this  specification  extends  through 
private  property,  all  excavated  material  not  required  for  the 
proper  construction  of  the  work,  and  all  standing  timber,  if 
claimed  by  the  owner  of  the  property,  shall  not  be  removed  from 
the  ground.  If  not  claimed  by  the  property  owner,  the  material 
shall  be  removed  and  the  ground  left  clean,  as  required  by  these 
specifications. 

Examination  of  Finished  Work.  The  Contractor  shall  fur- 
nish— if  deemed  advisable  by  the  Engineer — all  necessary  facili- 
ties for  making  an  examination  of  any  work  already  completed. 
If  the  work  is  found  defective  in  any  respect,  the  Contractor 
shall  defray  all  expense  of  such  examination  and  of  satisfactory 
reconstruction.  If  the  work  is  found  satisfactory,  such  expense 
will  be  allowed  for. 

Material  Specified.  "Where  materials  are  called  for  specifically 
by  name  of  the  manufacturer,  this  specification  is  intended  for  a 
standard  of  style  and  quality  only;  but  no  deviation  from  or 
substitution  for  this  material  will  be  permitted  without  written 
permission  from  the  Engineer. 

Risks  from  Floods,  etc.  The  Contractor  shall  assume  all 
risks  from  floods  and  casualties  of  every  description ;  all  damage 
to  grading,  bridges,  trestlework,  sewers,  masonry,  and  all  other 
kinds  of  work  not  herein  specified,  from  high  water,  rains,  fire, 
or  from  any  cause  whatsoever ;  and  the  work  so  damaged  shall  be 
replaced  at  the  expense  of  the  Contractor.  In  case  of  any  such 
accident  he  shall  give  immediate  notice  to  the  proper  authorities. 

Sanitary  Regulations.  Necessary  sanitary  conveniences  for 
the  use  of  laborers  on  the  work,  properly  secluded  from  public 
observation,  shall  be  constructed  and  maintained  by  the  Con-, 
tractor  in  such  a  manner  and  at  such  points  as  shall  be  approved 
by  the  Engineer,  and  their  use  shall  be  strictly  enforced. 

Shanties.  The  building  of  shanties  or  other  structures  for 
housing  the  men  will  be  permitted  only  at  such  places  as  the 
Engineer  shall  approve,  and  the  sanitary  condition  of  the  ground 
in  or  about  such  shanties  or  other  structures  must,  at  all  times, 
be  maintained  in  a  manner  satisfactory  to  the  Engineer. 

No  Spirituous  Liquors.  The  Contractor  shall  neither  permit 
nor  suffer  the  introduction  or  use  of  spirituous  liquors  upon  or 
about  the  works  embraced  in  this  contract,  or  upon  any  grounds 
occupied  by  him. 


240 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  21 

Roads  to  be  Opened.  The  Contractor  shall,  immediately  after 
signing  the  contract  for  the  work  under  this  specification,  pro- 
ceed to  open  and  maintain  such  good  and  safe  roads  and  paths 
for  foot  and  horse  travel,  along  the  whole  line  of  the  work  herein 
described,  as  the  Engineer  may  direct;  and  on  portions  of  the 
work  where  there  are  no  highways  convenient  for  the  wagoning 
of  supplies,  he  shall  open  and  maintain  such  wagon  roads  as  may 
be  directed  by  the  Engineer,  who  also  shall  decide  what  extra 
amount,  if  any,  he  shall  be  entitled  to  for  this  work. 

NOTE. — This  clause  is  applicable  only  to  such  classes  of  work  as  railroads, 
canals,  extensive  sewer  and  pipe-line  contracts,  and  reclamation  work. 

Contractor  Responsible  for  Violation  of  Laws.  In  all  opera- 
tions connected  with  the  work  embraced  in  this  contract,  the 
Contractor  shall  be  held  responsible  for  any  failure  to  respect, 
adhere  to,  and  comply  with  all  local  ordinances,  and  all  state  and 
national  laws  controlling  or  limiting  in  any  way  the  actions  of 
those  engaged  upon  the  work,  or  affecting  the  transportation  or 
disposition  of  the  materials.  He  shall  place  sufficient  lights  on 
or  near  the  work,  and  keep  them  burning  from  twilight  to  sun- 
rise ;  he  shall  observe  such  rules  relative  to  signals  and  safe- 
guards as  the  laws,  regulations,  or  ordinances  require ;  and  shall 
also  provide  watchmen  on  the  work  for  the  protection  of  the 
public. 

Liability  of  Contractor.  The  Contractor  shall  assume  all 
liability  for,  and  indemnify  the  company  against,  all  loss,  cost, 
or  damages  for  or  by  reason  of  any  liens,  claims,  or  demands  for 
materials;  all  loss  from  laborers,  mechanics,  and  others;  from 
any  damages  arising  from  injuries  sustained  by  mechanics, 
laborers,  or  other  persons,  by  reason  of  accidents  or  otherwise ; 
and  from  damages  sustained  by  depositing  materials  to  public 
injury,  or  to  the  injury  of  any  person  or  corporation  (including 
costs  and  expenses  of  defense),  provided  that  he  be  duly  notified 
of  the  bringing  of  suits  in  such  cases,  and  be  permitted  to  defend 
the  same  by  his  own  counsel,  if  he  should  so  elect. 

Other  Work  on  the  Company's  Land.  The  Company  reserves 
the  right  to  carry  on  its  construction  and  other  work,  outside 
that  enumerated  in  this  specification,  at  the  same  time  that  the 
Contractor  is  prosecuting  the  work  under  these  specifications; 
and  its  Engineer  shall  at  all  times  be  authorized  to  permit  others 
to  pass  over  or  haul  any  materials  over  the  Company's  land,  and 
perform  work  thereon,  having  at  all  times  due  regard  to  the  fact 
that  such  authority  given  to  him  shall  not  seriously  interfere 
with  or  impede  the  work  of  the  Contractor. 


241 


22  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Cleaning  up  Debris.  The  Contractor  shall  remove  all  false- 
work, piling,  and  other  unsightly  material  and  obstructions,  all 
debris  and  surplus  materials  from  the  site  of  the  work,  the  right 
of  way,  adjacent  properties,  highways,  and  thoroughfares  as  each 
piece  of  work  is  completed.  Channels  of  streams,  public  and 
private  roads,  and  streets  must  be  left  in  as  good  order  as  previous 
to  the  commencement  of  the  work,  and  in  a  condition  satisfactory 
to  the  Engineer  and  proper  authorities. 

INTERFERENCE  WITH  TRAVEL,  ETC. 

Obstruction  to  Travel.  Jhe  Contractor  shall  conduct  his 
work  in  such  manner  as  neither  to  obstruct  traffic  on  any  rail- 
road, highway,  or  thoroughfare,  on  land  or  water,  nor  interfere 
with,  nor  obstruct  the  use  of  private  property,  or  wagon  entrances, 
or  the  work  of  other  contractors  employed  at  the  site  of  the  work. 
In  case  of  accident  or  claim  for  damages,  due  to  the  Contractor's 
neglect  in  these  respects,  he  will  be  held  strictly  responsible  for 
any  such  claim  therefor. 

Interference  with  Traffic.  When  work  is  to  be  done  upon  or 
adjacent  to  a  railroad,  the  Contractor  shall  so  prosecute  his  work 
as  to  interfere  as  little  as  possible  with  the  traffic  of  such  rail- 
road ;  and  all  work  that  may  affect  the  safety  of  the  traffic  of  the 
same  shall  be  subject  to  the  direction  of  the  superintendent  of 
the  railroad  company  upon  which,  or  adjacent  to  which,  the  work 
is  being  carried  out. 

Where  the  work  under  this  contract  is  crossed  by  public  or 
private  roads,  the  Contractor  shall  provide  and  maintain  a  safe 
road  for  traffic,  and  the  work  shall  be  carried  on  in  such  a  manner 
as  not  to  obstruct  or  block  travel.  Where  directed  by  the 
Engineer,  temporary  crossings  shall  also  be  provided.  All 
material  excavated  or  delivered  shall  be  so  placed  as  not  to  inter- 
fere with  traffic. 

Watchmen  and  River  Signals.  The  Contractor  shall  provide 
at  his  own  expense  the  necessary  watchmen,  signals,  and  lights, 
and  must  observe  the  local  laws  of  the  district  in  protecting  the 
public  against  all  injury  and  damage.  He  shall  conform  to  all 
the  rules  and  laws  governing  navigation  in  the  waters  crossed  by 
structures  specified  in  this  contract,  and  shall  notify  the  proper 
authorities  of  the  location  of,  or  change  in  position  of,  proposed 
structures  and  plant  in  said  waters,  and  shall  establish  and  main- 
tain the  necessary  lights,  fog  signals,  etc.,  upon  structures  in 
course  of  construction,  and  upon  his  plant.  In  case  of  any  damage 
resulting  from  neglect  to  keep  and  maintain  suitable  lights  and 


242 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  23 

signals,  or  from  mistake  in  signals,  it  must  be  promptly  repaired 
at  the  expense  of  the  Contractor. 

Railroad  Crossings.  Where  the  work  is  to  be  constructed 
under  the  tracks  of  a  steam  railroad,  the  Contractor  will  be 
required  to  make  satisfactory  arrangements  with  the  railroad 
company  for  the  support  of  its  tracks. 

Water  and  Gas  Pipes— Drainage.  The  Contractor  is  required 
to  sling,  shore  up,  and  secure  in  their  places  all  water  and  gas 
pipes  and  electrical  conduits,  or  other  underground  structures 
encountered,  without  injury;  and  to  provide  for  and  maintain 
the  flow  of  water,  gas,  electricity,  drainage,  and  watercourses, 
whether  on  the  surface  or  underground,  which  may  be  inter- 
cepted or  interrupted  during  and  by  the  progress  of  the  work. 
Where  the  location  of  such  pipes,  drains,  etc.,  has  to  be  changed 
on  account  of  the  new  construction  or  its- appurtenances,  the 
Contractor  shall  bear  all  expenses  attending  such  changes. 

Restoring  Street  and  Road  Surfaces.  All  road  surfaces,  side- 
walks, and  paving,  disturbed  by  the  work  herein  described,  shall 
be  restored  to  their  original  condition  upon  the  completion  of 
the  work. 

DAMAGES,  CLAIMS,  ALTERATIONS,  ETC. 

Damage  to  Persons  and  Property,  Patents,  etc.  The  Con- 
tractor shall  be  responsible  for  all  damage  to  persons  and  to 
public  and  private  property;  for  trespassing,  or  for  any  other 
offense  committed  by  his  workmen  or  others  in  his  employ;  for 
damage  by  explosives,  fires,  or  any  other  causes  incident  to  the 
conduct  of  the  work.  Any  damage  resulting  from  neglect  of 
precautionary  provisions  by  the  Contractor  or  his  employes,  shall 
be  paid  for  by  the  Contractor  and,  if  necessary,  the  payments 
may  be  withheld,  at  the  option  of  the  Engineer,  until  such  damage 
is  satisfactorily  settled.  The  intention  of  the  contract  is  that  the 
Company  shall  not  be  held  responsible  for  any  claims  or  losses 
incurred  through  the  construction  of  the  work  herein  described. 

Suits,  Claims,  Patents.  The  Contractor  shall  indemnify  the 
Company  from  all  suits  and  actions  of  every  nature  and  descrip- 
tion brought  against  the  said  Company  for,  and  on  account  of, 
the  use  of  any  patents  or  infringements  of  patents  in  connection 
with  this  contract,  or  for  any  damages  or  injuries  received  and 
sustained  by  any  party  or  parties  in  the  performance  of  the  work 
under  this  agreement. 

Forfeiture  for  Overtime  —  Liquidated  Damages.  It  is  ex- 
pressly agreed  that  time  is  of  the  essence  of  this  contract,  and  the 
Contractor  agrees  that  the  Engineer  is  authorized  to  deduct  and 


243 


24  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

retain  permanently  out  of  the  moneys  which  may  be   due   or 
become  due  the  said  Contractor  under  this  contract,  the  sum 

of -...dollars  per  day  as  liquidated  damages, 

and  not  as  a  penalty,  for  each  and  every  day  that  the  work 
herein  described  remains  uncompleted  beyond  the  time  stipulated. 

NOTE. — This  claim  is  seldom  enforced  as  the  Company  may  have  to  prove 
that  it  has  been  damaged  to  the  amount  specified  and  that  such  damage  is 
entirely  due  to  the  delay  of  the  Contractor  in  completing  his  work.  Of  course, 
the  sympathy  of  the  Engineer  is  often  with  the  Contractor  who  is  behind 
with  his  work,  through  no  fault  of  his,  and  the  sympathy  of  the  jury  is 
generally  with  the  Contractor  and  workingman,  as  against  the  party  with 
money,  be  it  an  individual  or  a  corporation. 

NOTE. — When  the  penalty  for  the  noncompletion  of  work  on  time  is  pro- 
vided in  the  contract,  the  amount  of  same  may  be  recovered  from  the  Con- 
tractor by  legal  process;  but  if  the  Contractor  is  delayed  by  the  Company  at 
any  time  during  the  progress  of  the  work,  the  penalty  cannot  be  enforced  by 
the  Company. 

Should  the  Company  order  extra  or  additional  work,  for 
which  extra  time  is  allowed,  it  does  not  excuse  the  Contractor 
from  completing  the  work  on  time  nor  from  making  the  payment 
for  delay. 

Extra  Work.  The  Contractor  shall  do  any  extra  work,  not 
herein  otherwise  provided  for,  when  and  as  ordered  in  writing 
by  the  Engineer;  and  shall,  when  requested  by  the  Engineer  so 
to  do,  furnish  itemized  statements  of  cost  of  the  work  ordered; 
and  give  the  Engineer  access  to  accounts,  bills,  and  vouchers 
relating  thereto ;  nor  shall  any  claims  be  allowed  for  extra  work 
unless  the  same  shall  be  done  in  pursuance  of  a  written  order 
from  the  Engineer,  and  the  claim  made  at  the  first  settlement 
after  the  work  is  executed;  unless  the  Engineer,  at  his  discre- 
tion, shall  direct  the  claim,  or  such  part  of  it  as  he  may  deem 
just  and  equitable,  to  be  allowed ;  and  it  is  expressly  understood 
that  the  Contractor  agrees  to  accept  such  allowances  and  esti- 
mates in  full  satisfaction  of  such  extra  work,  loss,  or  damage, 
the  decision  of  the  Engineer  as  to  the  amount  of  such  extra 
work,  loss,  and  damage  being  as  final,  conclusive,  and  as  binding 
on  both  parties  as  though  the  said  extra  work  were  a  part  of 
the  work  specifically  described  in  this  contract. 

NOTE. — It  is  customary  for  the  Engineer  to  allow  from  10  to  15  per  cent 
for  profit  over  and  above  the  actual  cost  of  the  work,  which  should  include  the 
cost  of  superintendence  and  repair  of  tools. 

Alterations.  The  Engineer  may  from  time  to  time,  by  an 
instrument  in  writing  signed  by  him,  order  the  Contractor  to 
make  changes  in  the  work.  In  case  the  changes  so  ordered 


244 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  25 

make  the  work  less  expensive  to  the  Contractor,  a  proper  deduc- 
tion shall  be  made  from  the  contract  price,  and  the  Contractor 
shall  have  no  claim,  on  this  account,  for  damages  or  for  antici- 
pated profit  on  the  work  that  is  dispensed  with;  in  case  such 
changes  make  the  work  more  expensive,  a  proper  addition  shall 
be  made  to  the  contract  price;  such  deduction  or  addition  shall 
be  determined  by  the  Engineer.  In  case  of  any  change  ordered 
as  aforesaid,  or  in  case  any  other  changes  in  the  work  are  made 
by  the  mutual  consent  of  the  parties  hereto,  whether  affecting 
the  contract  price  or  not,  or  the  time  of  completion  or  not,  all 
and  each  of  the  other  provisions  qf  this  specification  shall  remain 
in  force  and  apply  to  the  contract  as  thus  altered.  Changes  so 
made  shall  not  make  void  any  bonds  that  may  have  been  given 
by  the  Contractor. 

Change  of  Line  and  Grade.  The  line  of  the  work  or  the 
gradients  or  elevations  may  be  changed,  if  the  Engineer  shall 
consider  such  change  necessary  or  expedient,  and  for  any  con- 
siderable alteration  the  injury  or  advantage  to  the  Contractor 
will  be  estimated,  and  such  allowance  or  deduction  made  in  the 
price  as  the  Engineer  may  deem  just  and  equitable ;  but  no  claim 
for  an  increase  in  prices  on  the  part  of  the  Contractor  will  be 
allowed  or  considered  unless  presented  in  writing  to  the  Engineer 
before  the  work  on  that  part  of  the  section  where  the  alteration 
is  to  be  made  shall  have  been  commenced. 

NOTE. — This  provision  is,  of  course,  applicable  to  railroads,  pipe  lines, 
canals,  sewers,  etc.,  and  hence  is  not,  strictly  speaking,  a  general  provision; 
but,  as  it  applies  to  many  kinds  of  work,  it  has  been  introduced  here. 

NOTE. — The  changing  of  plans  and  specifications  is  always  to  be  avoided, 
if  possible,  but  it  is  almost  impossible  to  write  a  faultless  contract  and  to 
foresee  all  conditions  that  will  arise.  After  the  beginning  of  construction, 
changes  must  sometimes  be  made.  The  right  of  the  Engineer  to  make  changes 
during  the  progress  of  the  construction,  while  customary,  should  generally  be 
limited  to  details  and  to  the  character  of  the  materials.  Of  course,  the  more 
perfect  the  plans  and  specifications,  the  fewer  alterations  will  be  required, 
and,  consequently,  the  fewer  demands  for  extra  compensation  for  unforeseen 
work.  Remember  that  changes  made  in  the  specification,  plans,  or  contract 
after  execution  are  not  binding  unless  they  are  known  and  agreed  to  by  both 
parties  to  the  contract,  in  which  case  all  should  be  noted  in  writing  on  the 
instrument  and  signed  by  both  parties  setting  forth  the  date  of  the  change. 
All  changes  on  drawings  should  be  made  in  a  conspicuous  color  and  be  carefully 
dated. 

PAYMENT,  LIENS,  ESTIMATE,  BOND,  ETC. 

Spirit  of  Specification.  The  ''spirit"  of  these  specifications 
is  to  furnish  all  material  and  workmanship  necessary  for  the 
construction  herein  described,  complete  in  every  respect,  for 


245 


26  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

the  purpose  for  which  it  is  designed ;  and  the  Contractor  is  hereby 
bound  to  consider  and  provide  for  any  workmanship  or  mate- 
rials, which  are  obviously  necessary  in  order  to  carry  out  the 
full  intent  and  meaning  of  the  plans,  details,  diagrams,  and 
specifications,  although  the  same  may  not  be  either  directly  or 
indirectly  noted  by  drawings  or  specifications.  He  shall  pro- 
vide, in  his  proposal,  for  the  said  omissions,  as  fully  as  though 
they  were  specifically  denoted,  and  shall  execute  the  same 
without  charge  or  claim  therefor. 

Payment.  Monthly  estimates  of  the  amount  of  work  done 
and  material  delivered  under  this  contract  shall  be  made  by  the 
Engineer  on  or  about  the  first  day  of  the  month;  and  from  the 
estimates  so  made,  the  value  of  the  work  done  and  of  the  material 
delivered  on  the  site  of  the  work  shall  be  determined.  Upon 
the  Contractor's  furnishing  a  complete  release  of  liens  for  all 
labor  and  material  furnished  to  the  time  of  the  taking  of  the 

said  estimate,  within days  the  Company  shall  pay 

the  Contractor- per  cent  of  the  amount  due,  as 

determined  by  the  Engineer,  and  this  method  of  payment  shall 
continue  until  the  work  under  this  contract  is  completed. 

The  balance  or  amount  remaining  unpaid  and  due  the  Con- 
tractor shall  be  paid  within days  after  the  final 

completion  and  acceptance  of  the  work  by  the  Engineer. 

NOTE. — Amount  of  Retained  Percentage.  To  insure  completion,  it  is 
customary  to  retain  from  10  to  20  per  cent  of  the  monthly  estimate  until  the 
work  is  finished.  In  very  large  contracts,  as  certain  sections  are  completed  and 
turned  over  to  the  Company,  the  retained  percentage  is  surrendered  to  the 
Contractor.  The  time  required  in  making  up  estimates,  forwarding  same  to 
headquarters,  auditing,  and  forwarding  check,  takes  from  10  to  30  days, 
depending  on  circumstances;  15  days  is  usually  ample  time  to  allow  for  these 
transactions. 

NOTE. — No  Claim  for  Payment  until  Work  is  Turned  Over.  The  Contractor 
can  make  no  claim  for  payment  until  the  materials  or  the  work  accomplished 
have  been  put  into  the  possession  of  the  Company.  Should  the  Company  decline 
to  accept  the  materials  or  work  after  same  has  been  turned  over  to  it,  the 
Contractor  may  then  bring  suit  to  compel  payment. 

NOTE. — No  Payment  until  Certain  Amount  Complete.  Payment  may  be 
made  by  installments  based  on  a  certain  amount  accomplished.  Under  such  an 
arrangement  the  Contractor  can  make  no  claim  for  payment  until  such  an 
amount  has  been  accomplished.  Should  the  Contractor  abandon  the  work  before 
such  an  amount  of  work  be  done,  he  could  not  recover. 

NOTE. — Accidents.  When  the  work  is  to  be  finished  before  payment  is 
made,  the  Contractor  must  stand  the  risk  of  fire,  flood,  or  other  accident;  but 
if  there  is  no  written  contract  or  custom  requiring  the  entire  construction  to  be 
completed  before  payment  is  made,  the  Contractor  may  recover  for  what  he  has 


246 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  27 

accomplished,  in  case  of  accident,  fire,  or  flood,  provided  it  can  be  proved  that 
he  used  all  proper  precautions. 

Some  contracts  require  the  Contractor  to  procure  and  present  certificates  of 
the  proper  fulfillment  of  contract  from  the  Engineer,  Inspector,  etc.,  before 
claim  is  made  for  payment. 

Eelease  of  Liens.  Before  the  final  payment  the  Contractor 
shall  give  the  Company  a  complete  release  of  liens  and  claims 
chargeable  to  said  Contractor;  and  if  at  any  time  any  liens  or 
claims  are  filed,  making  the  Company,  or  the  work,  or  construc- 
tion liable,  the  Company  has  the  right  to  retain  out  of  any  and 
all  payments  due,  or  to  become  due  to  said  Contractor,  amounts 
sufficient  completely  to  indemnify  the  Company,  work,  or  build- 
ings, against  such  liens-  and  claims;  and  in  the  event  of  any 
liens,  or  claims,  being  established  after  all  payments  have  been 
made  and  the  security  surrendered  to  the  Contractor,  the  Con- 
tractor is  to  pay  back  to  the  said  Company  all  money  or  moneys 
that  the  Company  may  have  been  compelled  to  pay  in  conse- 
quence of  such  liens  or  claims. 

NOTE. — It  is  of  the  greatest  importance  that  the  Company  be  protected 
against  liens  of  every  character.  In  cases  of  unsuccessful  contractors,  it  will 
be  found  that  laborers,  mechanics,  and  material  men  will  make  use  of  liens 
to  protect  themselves. 

Liens.  The  Contractor  shall  file  no  liens  for  any  labor  or 
material  furnished  under  this  contract;  such  waiver  of  liens, 
however,  shall  in  no  way  be  considered  as  a  waiver  of  action  by 
law  for  the  recovery  of  the  amount  due  the  Contractor  as  ap- 
proved or  awarded  by  the  Engineer;  it  is 'further  agreed  that 
no  subcontractor  for  work  or  material  and  no  laborer,  mechanic, 
or  any  person  whatsoever  shall  have  the  right  to  file  any  lien 
of  any  kind  for  any  sum  which  may  be  due  or  become  due  to 
him  under  this  contract,  or  for  work  and  material  furnished 
thereunder,  or  for  any  other  purpose,  and  his  right  to  file  such 
liens  is  expressly  waived. 

Monthly  Estimate  Subject  to  Variation.  Every  monthly  esti- 
mate shall,  for  the  time  being,  be  conclusive  upon  both  parties 
thereto,  but  being  made  (except  as  herein  provided  as  to  extra 
work)  merely  as  a  basis  for  payment  on  account,  though  with  a 
great  desire  and  effort  for  accuracy,  may  be  only  approximately 
correct,  and  therefore  shall  (except  as  herein  provided  as  to 
extra  work)  be  subject  to  correction  by  the  Engineer  in  any 
subsequent  monthly  estimate,  or  in  any  final  estimate.  No  such 
monthly  estimate  or  certificate  for  unfinished  work  shall  be  con- 
sidered or  taken  as  an  acceptance  of  the  work;  or  as  a  release 
of  the  Contractor  from  responsibility  therefor;  or  as  controlling 


247 


28  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

the  Engineer  in  the  final  certificate,  which  alone  shall  operate  as 
an  acceptance  of  the  work  or  as  a  release  of  the  Contractor. 

Contractor's  Bills  in  Arrears.  If  at  any  time  it  shall  be  found 
that  the  Contractor's  bills  for  material  or  labor  are  not  being 
paid  within  a  reasonable  time,  the  Company  may  withhold  from 
the  Contractor's  monthly  estimate  a  sufficient  amount  to  cover 
the  said  bills,  and  the  Company  shall  apply  the  amount  so  with- 
held to  the  payment  of  said  debts. 

Abandonment  or  Violation  of  Contract.  Should  the  Con- 
tractor neglect  or  abandon  the  work,  or  should  the  Engineer  at 
any  time  be  convinced  that  the  work  is  unreasonably  delayed,  or 
that  the  conditions  of  the  contract  are  being  wilfully  violated, 
or  executed  carelessly,  or  in  bad  faith,  he  may  notify  the  Con- 
tractor in  writing  and,  if  his  notification  be  without  effect  within 
24  hours  after  the  delivery  thereof,  then  and  in  that  case  the 
Contractor  shall  discontinue  all  work  under  the  contract,  and 
the  Engineer  shall  have  full  authority  and  power  immediately 
to  enter  upon  and  take  possession  of  the  work,  plant,  tools,  and 
materials;  and  to  purchase  and  hire  materials,  tools,  labor,  ani- 
mals, and  machinery  for  the  completion  of  the  contract  at  the 
expense  of  the  Contractor,  or  his  sureties,  or  both;  or  the  said 
Engineer  may  declare  the  contract  null  and  void,  in  Avhich  case 
the  security  bond,  the  retained  percentage,  the  materials  built 
into  the  work,  and  the  materials  delivered  shall  then  become 
the  property  of  the  Company. 

In  case  either  of  the  above  methods  is  resorted  to,  the  Com- 
pany shall  have  the  right  to  use  the  plant,  animals,  and  materials 
until  the  completion  of  the  work;  and  should  the  amount  re- 
tained on  the  previous  estimates  be  insufficient  to  pay  all  bills 
in  connection  with  the  work,  the  Company  shall  have  the  right 
to  sell  as  much  of  the  Contractor's  plant  and  tools  as  shall  be 
sufficient  to  make  good  the  deficit.  Upon  the  completion  of  the 
work  the  plant  and  tools,  or  those  that  may  remain  in  case  it  is 
necessary  to  make  such  sale,  shall  be  turned  over  to  the  Con- 
tractor. 

Right  to  Suspend  Work.  The  Engineer  reserves  the  right 
to  suspend  or  terminate  the  work  embraced  in  these  specifica- 
tions for  reasons  not  herein  specified,  and  the  Contractor  shall 
discontinue  all  work  within  10  days  after  receiving  notice  of 
such  suspension  or  termination;  in  which  case,  the  Contractor 
shall  be  entitled  to  payment  in  full  for  all  materials  actually 
handled  or  supplied,  at  a  valuation  to  be  fixed  by  the  Engineer, 
but  shall  make  no  claim  for  consequential  damages  or  antici- 
pated profits  upon  work  not  actually  performed,  or  damage  of 
any  kind  resulting  from  such  suspension  or  termination. 


248 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  29 

Agreement.  The  successful  bidder,  upon  notice  from  the 
Company,  shall  at  once  furnish  it  with  the  names  of  the  sureties 
to  be  offered,  and  shall  execute  the  agreement  and  furnish  the 

executed  bond  within days  from  the  date  of  mailing 

of  notice  to  the  said  bidder  that  the  contract  is  ready  for  sig- 
nature; and  in  case  of  failure  or  neglect  to  do  so,  he  will  be 
considered  to  have  abandoned  the  contract,  and  the  check 
accompanying  the  proposal  shall  be  forfeited  to  the  Company. 

Bond.  The  Contractor  will  be  required  to  give  an  approved 

surety  company  bond  to  the  Company  in  the  sum  of 

dollars  for  the  faithful  execution  of  the 

work  under  this  specification;  for  keeping  in  perfect  repair  and 
good  order  all  of  the  new  work  constructed  hereunder;  for  all 
breakage  or  other  damage  that  may  occur  to  any  works  that 

may  be  within  the  lines  of  the  work  herein  described,  for 

years  after  date  of  final  payment ;  for  the  prompt 

payment  for  labor  and  materials  used  in  the  work;  and  for  the 
protection  of  the  Company  from  all  claims  on  patents,  or  damages 
to  persons  or  property  caused  -by  the  negligence  of  the  Con- 
tractor or  his  employes  in  connection  with  the  work  herein  de- 
scribed; and  it  is  understood  that  such  surety  shall  not  in  any- 
wise be  released  by  any  modification  or  alteration  in  this  con- 
tract agreed  upon  between  the  parties,  the  said  bond  being  ex- 
pressly subject  to  said  modifications  or  alterations.  Said  bond 

shall  be  surrendered months  after  the  date  of 

completion  and  acceptance  of  the  work  executed  hereunder. 

NOTE. — Avoid  personal  bonds;  good  trust  company  bonds  are  secured 
readily  by  good  contractors  and  are  much  more  satisfactory  to  the  Company. 

TYPICAL  ILLUSTRATIVE  SPECIFICATIONS 

The  various  groups  of  clauses  which  have  just  been  given 
under  the  head  of  General  Provisions  are,  as  the  heading  indi- 
cates, intended  to  cover  the  general  features  of  any  well-drawn 
set  of  specifications.  The  typical  specifications  which  follow 
give  a  clear  idea  of  the  nature  of  the  provisions  required  for 
special  kinds  of  work,  the  selections  being  sufficiently  varied  in 
character  to  cover  the  usual  types  of  contract. 

RAILROAD  GRADING 

Tools,  Materials,  and  Labor.  The  Contractor  shall,  at  his 
own  expense,  cost,  and  charge,  find  and  provide  a  full  and  ample 
supply  of  the  best  and  most  suitable  tools  and  appliances  required 


249 


30  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

to  be  used  in  the  performance  of  the  work  to  be  executed  under 
this  contract;  he  shall  provide  the  best  materials  of  every  kind 
that  may  be  needed  for  the  thorough  and  expeditious  execution 
of  said  work;  and  he  shall  furnish  and  provide  in  sufficient 
numbers  all  mechanics,  laborers,  and  other  workmen,  and  also 
all  things  that  may  be  requisite  and  necessary  for  constructing 
and  completing,  within  the  time  herein  stipulated,  the  whole  of 
the  work  herein  agreed  to  be  done. 

Location  of  Work.     The  work  covered  by  this  specification  is 

on  the  line  of  the Railroad  which 

is  located  between in :  County   and 

in County,  all  lying  in  the  State 

of -- The    section    extends    from    Station 

_ to  Station and  involves  princi- 
pally clearing,  grubbing,  grading,  trestling,  masonry,  pipe, 
masonry  or  timber  culverts. 

GRADING  SPECIFICATIONS 

Under  this  head  shall  be  included  all  the  clearing  and  grub- 
bing, all  excavation  and  embankment  required  for  the  formation 
of  the  roadbed  ready,  for  the  track ;  cutting  of  ditches  or  drains 
about  or  contiguous  to  the  road ;  widening  or  changing  channels 
for  streams  or  watercourses ;  the  construction  of  farm  crossings ; 
the  foundation  of  culverts  and  bridge  masonry,  walls  or  bridges ; 
reconstruction  of  mill  races,  highways,  and  roads  where  they 
are  interfered  with  or  destroyed  in  the  formation  of  the  road- 
way; also  the  furnishing  and  erecting  of  all  masonry,  trestling, 
planking,  piling,  pumping,  bailing,  and  all  the  excavation  and 
embankment  in  any  way  connected  with  or  incident  to  the  con- 
struction of  said  railroad. 

The  road  shall  be  graded  in  conformity  with  such  directions 
as  the  Chief  Engineer  may  give  concerning  breadths,  depths, 
and  slopes  of  excavation  and  embankment. 

Clearing.  The  lands  of  the  railroad  company  shall  be  cleared 
to  the  full  extent  of  the  right  of  way  of  all  trees,  logs,  bushes, 
and  other  perishable  matter,  which  shall  be  destroyed  by  burning, 
or  deposited  in  heaps,  as  the  Engineer  may  direct.  Large  trees 
must  be  cut  not  more  than  1  foot  from  the  ground  and,  under 
embankments  less  than  4  feet  high,  they  shall  be  cut  even  with 
the  surface  of  the  ground.  The  top  of  stumps  shall  not  be  less 
than  3  feet  below  subgrade  under  embankments.  All  small  trees 
and  bushes  shall  be  cut  even  with  tlie  ground.  The  burning  of 
brush  must  be  done  in  such  a  manner  as  not  to  endanger  adjacent 
timber  land  or  property.  Clearing  shall  be  paid  for  by  the  acre 


250 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  31 

or  fraction  thereof,  to  the  extent  indicated  by  the  Engineer  by 
stakes  or  by  marks  on  the  ground  or  timber.  All  trees  which 
the  Engineer  may  reserve  shall  be  stripped  of  their  tops  and 
branches,  cut  to  such  lengths,  and  be  neatly  piled  at  such  places, 
on  the  right  of  way,  as  the  Engineer  may  direct. 

Grubbing.  All  stumps,  roots,  muck,  and  perishable  material 
shall  be  grubbed  out  and  removed  from  all  places  where  embank- 
ments occur  less  than  2  feet  in  height.  All  stumps  grubbed  out 
shall  be  burned.  Until  the  Contractor  is  notified  that  the  work 
done  on  the  surface  to  be  grubbed  is  satisfactory  to  the  Engineer, 
no  embankment  shall  be  made  on  such  surface.  Grubbing  is  to 
be  paid  for  by  the  acre  or  fraction  thereof  actually  grubbed. 

Excavation.  All  material  shall  be  measured  in  the  excava- 
tions, and  estimated  by  the  cubic  yard,  and  shall  be  classified 
under  the  following  heads,  viz :  solid  rock,  loose  rock,  earth, 
foundation  excavation  in  water,  and  ditching  in  earth. 

Solid  liocJc.  Solid  rock  shall  include  all  rock  which  will  ring 
under  the  hammer,  which  is  found  in  ledges  and  detached  masses 
exceeding  1  cubic  yard  each;  and  which,  in  the  judgment  of 
the  Engineer,  may  be  best  removed  by  blasting. 

Loose  Rock.  Loose  rock  shall  include  all  kinds  of  hard  shale, 
slate,  soapstone,  detached  stones  of  less  than  1  cubic  yard  and 
more  than  3  cubic  feet,  and  all  rock  which,  in  the  judgment  of 
the  Engineer,  cannot  be  plowed  and  which  can  be  removed  with 
pick  and  bar,  and  is  soft  and  loose  enough  to  be  removed  with- 
out blasting,  although  blasting  may  be  resorted  to  in  order  to 
facilitate  the  work. 

Earth.  Earth  shall  include  clay,  sand,  loam,  gravel,  and  all 
other  matter  of  an  earthy  nature,  of  whatsoever  name  or  char- 
acter, not  unquestionably  rock  as  above  defined.  Boulders  or 
detached  stones  containing  less  than  3  cubic  feet  shall  be  classified 
as  earth. 

Excavation  in  Water  for  Bridge  or  Culvert  Foundation.  Foun- 
dation excavation  in  water  shall  apply  to  material  below  the 
natural  water  surface  and  only  in  cases  where  (through  no  fault 
or  delay  of  the  Contractor)  constant  unavoidable  pumping  or 
bailing  is  a  necessity,  and  where  draining  by  a  ditch  would  be 
too  expensive  or  impossible ;  the  material  shall  be  classified  as 
excavation,  and  the  price  shall  include  the  necessary  cofferdams, 
caissons,  sheeting,  shoring,  draining,  bailing,  and  pumping  of 
water,  and  the  benching  and  dressing  of  the  rock  for  base  of 
masonry.  Where  unnecessary  delay  occurs  in  finishing  a  foun- 
dation promptly  in  dry  weather,  it  will  be  at  the  Contractor's 
risk,  as  regards  the  excavation,  in  case  water  is  met. 


251 


32  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Embankments.  Embankments  shall  generally  be  made  in 
horizontal  layers,  crowned  in  the  middle,  in  accordance  with 
the  instructions  of  the  Engineer,  and  shall  consist  of  materials 
which,  in  his  judgment,  are  suitable ;  they  shall  be  built  of  such 
width  and  carried  to  such  height  above  grade  as  the  Engineer 
may  deem  necessary  to  provide  for  shrinkage,  compression,  wash- 
ing, drainage,  and  settlement,  and  must  be  maintained  to  their 
proper  height,  width,  and  shape  until  accepted  by  the  Engineer. 
No  large  stone  will  be  allowed  within  a  depth  of  at  least  2  feet 
below  grade ;  the  best  materials  must  in  all  cases  be  reserved  for 
finishing  and  dressing  the  surfaces.  "Whenever  the  embankment 
is  made  from  the  side  ditches,  such  ditching  and  the  crest  of* 
the  slopes  thereof  shall  in  no  case  approach  within  6  feet  of  the 
foot  of  the  embankment  slopes,  and  the  slopes  of  such  ditching 
next  to  the  embankment  shall  not  be  steeper  than  the  slope  of 
the  embankment.  Whenever  new  watercourses  or  channels  are 
required  to  be  formed,  they  shall  be  put  at  such  distances  from 
the  foot  of  the  slopes  as  the  Engineer  may  direct. 

No  perishable  materials  will  be  allowed  in  embankments.  All 
proper  materials  taken  from  the  excavation  on  the  line  of  the 
railroad  shall  be  placed  in  the  embankment,  and  all  surplus 
materials  shall  be  used  in  widening  embankments  in  such  manner 
as  the  Engineer  may  direct. 

The  subgrade  must  be  compact  and  finished  to  agree  with 
the  standard  roadbed  section,  and  no  depression  that  would  hold 
water  shall  be  left.  - 

Embankments  about  Culverts.  Embankments  about  masonry 
and  pipe  culverts  and  bridges  shall  be  built  at  such  times,  and 
in  such  manner,  and  of  such  material  as  the  Engineer  may  direct. 
Embankments  shall  be  carried  forward  in  the  usual  way  to  within 
10  feet  of  any  bridge  or  culvert,  finished  or  in  progress,  from 
which  point  the  earth  shall  be  carefully  rammed  to  such  width, 
depth,  slopes,  and  in  such  manner  as  the  Engineer  may  direct. 
No  additional  prices  shall  be  allowed  for  this  work. 

Borrow  Pits  and  Spoil  Banks.  In  all  cases  where  the  excava- 
tions are  insufficient  to  make  the  embankments,  the  deficiency 
shall  be  supplied  by  widening  the  excavations,  or  it  shall  be  sup- 
plied from  borrow  pits,  as  the  Engineer  may  direct,  and  all  such 
excavations  and  borrow  pits  shall  be  located,  drained,  and  sloped 
as  the  Engineer  may  direct.  No  borrow  pit  shall  be  opened 
until  same  has  been  staked  out  on  the  ground  by  the  Engineer 
in  charge.  All  excavations  and  borrow  pits  shall  be  left  in  such 
shape  that  they  can  be  readily  measured. 

Any  surplus  material  taken  from  the  excavation  and  not  re- 
quired for  embankments,  or  other  purposes,  shall  be  deposited 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  33 

evenly  on  either  side  of  the  embankment,  as  the  Engineer  may 
direct,  and  shall  in  no  case  be  raised  above  the  grade  of  the  road. 

Ditches.  In  cuts,  ditches  shall  be  dug  along  the  foot  of  the 
slopes,  of  such  dimensions  as  the  Engineer  may  direct.  To  pro- 
tect the  cuts  from  washing,  intercepting  ditches  shall  be  dug 
above  the  cutting,  upon  ground  sloping  toward  the  cuts,  and 
connected  with  the  embankment  ditches,  when  directed  by  the 
Engineer;  and  if  the  material  from  such  ditches  is  wasted,  it 
shall  be  deposited  between  the  ditch  and  the  cut.  Such  exca- 
vation shall  be  paid  for  as  part  of  the  ordinary  excavation  of 
the  section. 

Ditches  for  changing  the  flow  of  streams  and  for  draining 
marshes,  ponds,  etc.,  shall  be  cut  of  such  dimensions  and  the 
materials  shall  be  so  deposited  as  the  Engineer  shall  direct ;  the 
same  to  be  paid  for  at  the  price  named  in  the  proposal  for 
"Ditching  in  Earth". 

Valuable  Material  and  Timber.  All  materials  taken  from  the 
excavations,  which,  in  the  judgment  of  the  Engineer,  may  be  of 
greater  value  to  the  railroad  company  for  other  purposes  than 
embankments,  and  also  all  timber,  removed  from  the  line  of  the 
railroad,  shall  be  considered  the  property  of  the  Railroad  Com- 
pany, and  shall  be  deposited  in  convenient  positions,  under  the 
direction  of  the  Engineer. 

Slips  and  Falls.  All  slips  and  falls  of  slopes  attributable,  in 
the  opinion  of  the  Engineer,  to  excessive  use  of  powder,  negli- 
gence, or  carelessness  of  the  Contractor  shall  be  removed  by  the 
Contractor  at  his  own  cost;  but  if  not  so  attributable,  an  allow- 
ance, to  be  fixed  by  the  Engineer,  shall  be  made  for  such  removal 
as  "Earth  Excavation". 

Measurements.  Clearing  shall  be  paid  for  by  the  acre  or 
fraction  thereof.  The  clearing  of  scattered  trees  shall  be  paid 
for  by  the  approximate  area  of  the  surface  of  ground  covered 
by  their  branches  before  being  felled.  Grubbing  shall  be  paid 
for  by  the  acre  or  fraction  thereof,  of  surface  actually  grubbed. 
The  Contractor  shall  give  the  Engineer  at  least  48  hours'  notice 
previous  to  beginning  the  making  of  embankments  on  surface 
grubbed,  and  the  same  shall  not  be  paid  for  unless  it  shall  have 
been  measured  by  the  Engineer,  and  the  Contractor  shall  have 
been  given  a  written  order  to  proceed  with  the  embankment  on 
the  surface  in  question. 

Materials  in  excavations  shall  be  measured  whenever  pos- 
sible, and  the  term  "excavation"  shall  include  all  cuttings,  bor- 
row pits,  roadways,  changes  of  watercourses,  ditches,  founda- 
tions, and  trestle  pits,  and,  in  .fact,  every  kind  of  excavation 
required  at  any  time  in  the  course  of  the  work. 


253 


34          CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Excavation,  in  all  the  several  classes  thereof,  shall  be  of  such 
dimensions  and  slope  as  the  Engineer  may  direct,  and  shall  be 
estimated  and  paid  for  by  the  cubic  yard,  and  no  allowance 
whatever  shall  be  made  for  overhaul.  The  price  for  excavation 
shall  include  all  the  necessary  sheeting,  shoring,  pumping,  and 

bailing.     For  the  material  to  be  excavated    (under  the 

Railroad    from Station    to 

7 Station)  for  the  roadbed  and  for  abutment  walls, 

a  special  price  will  be  paid,  as  named  in  the  proposal,  which 
price  for  excavation  shall  cover  the  sheathing  of  excavation  and 
supporting  of  tracks  in  a  manner  satisfactory  to  the  Chief 
Engineer  of  the Railroad  Company. 

GENERAL  CONDITIONS  AND  PROVISIONS 

Duties  of  Contractor.  Contractors  shall  satisfy  themselves  by 
a  careful  personal  examination  of  the  nature  and  location  of  the 
work  they  bid  for,  of  the  general  form  of  the  surface  of  the 
ground,  and  all  other  matters  which  can  in  any  way  influence 
their  contract;  and  no  information  upon  such  matters  derived 
from  the  maps,  plans,  profiles,  drawings,  or  specifications;  or 
from  the  Engineer  or  his  assistants,  shall  in  any  way  relieve  the 
Contractor  from  any  risk,  or  from  fulfilling  any  of  the  terms  of 
this  agreement. 

Interference  with  Traffic.  When  work  is  to  be  done  upon 
or  adjacent  to  a  public  or  private  road,  or  to  a  line  of  railway 
in  use,  the  Contractor  shall  so  prosecute  his  work  as  to  inter- 
fere as  little  as  possible  with  the  traffic  of  the  railway,  or  the 
traffic  of  such  public  or  private  road.  And  all  work  that  may 
affect  the  safety  of  the  railway  traffic  shall  be  subject  to  the 
direction  of  the  Division  Superintendent  of  the  railway  com- 
pany. "When  it  is  necessary  to  support  the  tracks  of  the  railway, 
the  railway  company  will  furnish  and  place  all  of  the  necessary 
timbers  for  this  work,  but  the  Contractor  shall  do  all  the  exca- 
vating therefor. 

Property  on  Right  of  Way.  Fences,  buildings,  timber,  and 
wood  on  the  right  of  way  along  the  line  of  the  road  are  the 

property  of  either  the  landowner,  or  the  party  of  the 

part ;  and  if  not  removed  by  the  landowner  within  a  reasonable 
time,  shall  be  cleared  off  by  the  Contractor,  and  shall  be  piled 

up,  and  preserved  for  the  use  of  the  party  of  the part, 

without  charge. 

Damages.  In  case  one  portion  of  the  work,  contracted  to  be 
done  in  accordance  with  these  specifications,  is  delayed  through 
the  negligence  or  incompetence  of  a  contractor  for  some  other 


254 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  35 

portion  of  the  work,  whatever  damage  may  result,  or  whatever 
expense  may  be  incurred  by  the  Contractor  so  delayed,  because 
of  such  negligence  or  incompetence,  the  amount  of  damage  or 
expense  shall  be  charged  to  the  contractor  at  fault,  and  the 
Engineer  shall  decide  the  amount  so  to  be  charged ;  and  the  party 
of  the  second  part  shall  in  no  wise  be  responsible  therefor,  or 
for  the  payment  therefor  by  the  other  contractor. 

Roads  to  be  Opened.  Contractors  having  work  awarded  to 
them  shall,  immediately  after  signing  their  contracts,  proceed  to 
open  and  maintain  such  good  and  safe  roads  and  paths  for  foot 
or  horse  travel  along  the  whole  line  of  their  sections,  as  may 
be  directed  by  the  Engineer;  and  on  portions  of  the  line  where 
there  are  no  highways  convenient  for  the  wagoning  of  supplies, 
they  must  open  and  maintain  such  roads,  and  the  Engineer  shall 
decide  what  extra  amount,  if  any,  they  will  be  entitled  to  for 
this  work. 

Any  person  having  permission  from  the  Engineer  shall  be 
allowed  to  pass  along  or  haul  any  materials  required  for  the  road 
over  any  section,  provided  such  persons  do  not  interfere  with 
or  impede  the  work  of  the  Contractor. 

Marks  and  Stakes  to  be  Preserved.  Contractors  shall  care- 
fully preserve  bench  marks  and  stakes  and,  in  case  of  willful  or 
careless  neglect  of  these,  they  shall  be  charged  whatever  the 
Engineer  shall  consider  an  equitable  amount  to  cover  damages 
arising  from  such  negligence. 

All  excavations  and  embankments  shall  conform  to  the  line 
and  stakes  set  out  by  the  Engineer,  and  any  excess  of  excavation 
or  waste  of  material  required  for  embankment  at  the  mouth  of 
cuts,  due  to  neglect  of  these  lines  and  stakes,  shall  not  be  esti- 
mated or  paid  for. 

Contractors  shall  clear  away  the  surplus  stone  and  wreckage 
from  masonry  sites  after  the  jobs  are  done;  and,  before  the 
completion  of  each  section,  remove  from  adjacent  properties, 
bermes,  and  highways  the  blasted  rock  and  all  other  debris  accu- 
mulated during  construction. 

Grade.  The  word  "grade"  whenever  herein  used  refers  to 
the  surface  of  the  roadbed  as  completed  and  prepared  for  the 
reception  of  the  ballast. 

Acknowledgment.  These  specifications  are  hereby  acknowl- 
edged, accepted,  and  made  part  of  this  agreement. 

Claims  for  Labor  or  Material.  It  is  hereby  agreed  that  no 
lien  nor  claim  shall  be  filed  by  anyone  for  the  work  or  labor  to 
be  done  or  the  materials  to  be  furnished,  under  or  in  pursuance 
of  this  contract. 


J855 


36  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

FOUNDATIONS 

General  Specifications.  Foundations  for  masonry  shall  be 
excavated  to  such  depths  as  may  be  necessary  to  secure  a  bearing 
which  is  satisfactory  to  the  Engineer.  In  case  of  foundations 
in  rock,  the  rock  shall  be  excavated  to  such  depths  and  in  such 
form  as  may  be  required  by  the  Engineer,  and  shall  be  dressed 
approximately  level  to  receive  the  foundation  course.  Materials 
excavated  shall  be  paid  for  as  provided  for  under  "Excavation". 

Special  Foundations.  Should  the  bottom  as  found  be  not 
satisfactory,  special  foundations  shall  be  constructed  of  concrete, 
reinforced  concrete,  or  of  timber  piling  or  platforms,  as  directed, 
and  in  accordance  with  plans  to  be  furnished.  If  work  of  special 
character  be  required,  the  Contractor  shall  be  paid  for  it  at  the 
special  prices  named  in  the  proposal,  and  said  prices  shall  include 
all  materials  and  all  labor  necessary  for  placing  it  in  the  work. 

Piles.  Piles  shall  be  of  white  oak,  long-leaf  yellow  pine,  or 
spruce  pine,  as  directed ;  sound,  of  straight  growth,  not  less  than 
8  inches  in  diameter  at  the  small  end,  and  not  less  than  12  inches 
at  the  butt  end  when  sawed  off.  They  shall  be  trimmed  close, 
barked  if  required,  pointed  or  shod  as  directed,  and  hooped  to 
prevent  splitting.  They  shall  each  be  of  one  piece  without 
splicing  or  doweling.  They  shall  be  driven  with  a  hammer 
weighing  at  least  2500  pounds,  to  refusal,  or  to  the  point  directed, 
in  straight  rows,  and  shall  be  sawed  off  truly  level.  If  any  piles 
are  raised  by  the  subsequent  driving  of  others,  they  shall  be  re- 
driven.  If  any  piles  be  driven  too  low  to  be  cut  off  or  fitted  at 
the  required  elevation,  proper  piles  shall  be  substituted.  Piles 
split  or  otherwise  injured  shall  be  replaced  or  repaired  as  directed. 

The  piles  in  place  shall  be  paid  for  at  the  price  per  lineal  foot 
given  in  the  proposal.  No  part  of  the  pile  shall  be  paid  for 
except  that  which  remains  in  the  work. 

Pile  Shoes.  Pile  shoes,  when  required,  shall  be  paid  for  as 
additional  steel.  They  shall  be  chilled  points,  4  inches  square  at 
the  point  of  the  pile,  with  4  straps  of  approved  size,  fastened 
with  8  three-eighths-inch  by  4-inch  spikes  to  the  pile,  which  shall 
be  properly  fitted  to  give  a  square  and  even  bearing  on  the  shoe. 

MASONRY 
GENERAL  CLAUSES 

Stone,  General.  Stone  masonry  shall  be  built  of  the  kinds  of 
stone  specially  designated,  with  such  arrangement  of  courses  and 
bonds  as  is  directed  or  shown  on  the  plans.  The  stone  shall  be 
hard  and  durable,  as  large  as  practicable  for  the  work,  of  ap- 
proved quality  and  shape,  and  in  no  case  having  less  bed  than  rise. 


256 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  37 

Laying.  Stone  masonry  shall  be  laid  with  the  stones  on  their 
broadest  beds,  well  bonded  and  solidly  bedded. 

All  walls  shall  be  laid  up  in  cement  mortar,  cement  grout 
being  used  to  fill  all  vertical  joints  which  cannot  be  thoroughly 
filled  with  mortar,  and  the  stone  shall  be  thoroughly  wetted 
when  it  is  laid.  All  walls  shall  be  made  as  water-tight  as  pos- 
sible. The  face  and  back  of  the  walls  shall  be  carried  up  to- 
gether. No  hammering  on  the  wall  shall  be  allowed  after  the 
stone  is  set;  if  any  inequalities  occur,  they  shall  be  carefully 
pointed  off. 

Clean  Walls.  The  showing  face  of  all  walls  shall  be  left  thor- 
oughly clean  upon  the  completion  of  the  work. 

Setting.  Dressed  stone  shall  be  set  with  a  lewis  if  required ; 
and  where  dressed  stone  is  bedded  in  mortar  it  shall  be  settled 
on  the  bed  with  a  wooden  maul. 

Concrete  Coping.  Concrete  coping  shall  be  composed  of  1-3-6 
concrete  as  specified,  built  to  the  dimensions  shown  on  the  plans. 
The  top  and  sides  shall  be  treated  as  specified  under  the  para- 
graphs relating  to  exposed  surfaces  of  concrete.  If  made  as  a 
monolith  on  top  of  the  wall,  the  coping  shall  be  cut  into  such 
lengths  as  may  be  directed.  Payment  shall  be  made  at  the  price 
per  cubic  yard  for  "Concrete  Coping"  in  the  proposal,  which 
price  shall  include  the  cost  of  all  forms,  etc. 

Concrete  coping  may  be  made  as  an  artificial  stone.  If  so 
made,  the  length  of  the  blocks  and  all  details  shall  be  approved 
by  the  Engineer. 

Back  Walls.  Where  stone  is  used  for  back  walls,  it  shall  be 
laid  as  stretchers  and  extend  through  the  wall  without  being 
backed  with  other  masonry;  the  faces  shall  be  rough-pointed. 
Back  walls  shall  be  capped  with  a  regular  course,  peen-hammered 
on  top.  Generally,  they  shall  not  be  built  until  the  superstructure 
has  been  placed  in  position. 

Bridge  Seats  and  Pedestal  Blocks.  Where  bridge  seats  and 
pedestal  blocks  are  of  stone,  approved  granite  *  shall  be  used. 
The  top  surfaces  under  the  bearings  of  trusses,  main  girders, 
columns,  or  other  principal  metal  bearings  shall  be  bushham- 
mered  and  the  remainder  of  the  upper  surfaces  shall  be  peen- 
hammered.  The  showing  edges  of  bridge  seats,  pedestals,  and 
caps  shall  be  rough-pointed.  Bushhammers  shall  have  5  cuts 
per  inch. 

Concrete  Bridge  Seats  and  Pedestal  Blocks.  Where  bridge 
seats  and  pedestal  blocks  are  of  concrete,  they  shall  be  composed 
of  1-2-4  concrete,  made  with  three-fourths-inch  stone,  as  specified, 
and  built  to  the  dimensions  shown  on  the  plans,  with  a  hard 
trowel  finish  on  all  showing  faces.  Payment  shall  be  made  at  the 


257 


38  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

special  price  per  cubic  yard  named  in  the  proposal,  which  price 
shall  include  the  cost  of  all  forms,  etc. 

Finish  of  Walls  not  Coped.  The  top  of  the  masonry  when 
not  covered  by  a  coping  shall  be  finished  with  large  stones 
selected  for  the  purpose,  which  will  give  an  approximately  flat 
surface. 

Pointing.  The  joints  on  faces  of  masonry  above  the  founda- 
tion shall  be  cleaned  out  to  a  depth  of  1  inch,  wetted,  and  pointed 
with  Portland  cement  mortar  well  and  securely  pressed  into  the 
joints;  the  whole  work  shall  have  a  neat  and  clean  finish.  Cut- 
stone  work  shall  be  hollow-pointed ;  all  other  masonry  shall  be 
cut-pointed. 

New  Masonry  on  Old.  When  new  masonry  is  laid  on  old 
masonry,'  the  latter  shall  be  cleaned,  wetted,  and  thoroughly 
grouted  before  laying  new  work.  All  new  work  shall  bond  with 
the  old.  The  new  face  stones  shall  match  the  old. 

Dressing  before  Setting.  All  cutting  and  dressing  necessary 
shall  be  done  before  the  stones  are  set,  and  by  skilled  workmen. 
Under  no  circumstances  shall  the  hammering  or  dressing  of 
stone  upon  the  walls  be  allowed.  The  stones  shall  be  placed  in 
position  so  as  not  to  disturb  those  previously  laid. 

Dressing.  In  all  classes  of  work,  the  faces  of  the  stone  shall 
have  uniform  projections,  not  exceeding  3  inches  beyond  the 
neat  lines.  All  projecting  angles  and  arrises  shall  have  hammer- 
dressed  beds  and  joints  and  shall  be  run  with  a  neat  chisel  draft 
of  1£  inches  on  each  face. 

Mortar  Joints.  Mortar  joints  in  the  face  of  the  wall,  in  first- 
class  and  second-class  work,  shall  not  exceed  one-half  inch  in 
thickness.  The  vertical  joints  of  the  face  shall  be  in  contact  at 
least  1  foot  in  first-class  and  9  inches  in  second-class  work,  meas- 
ured in  from  the  face,  and  as  much  more  as  the  stone  will  admit. 

Dashing  Backs  of  Walls.  The  joints  on  the  back  of  all 
masonry  walls  shall  be  carefully  and  thoroughly  dashed  with 
cement  mortar  so  as  to  make  the  walls  as  nearly  water-tight  as 
possible. 

When  the  back  of  a  wall  adjoins  rock,  it  shall  be  built  tight 
against  the  rock  and  the  joint  shall  be  thoroughly  grouted. 

Dry  Stone  Packing.  Dry  stone  packing  shall  consist  of  stone 
laid  without  mortar,  and  the  stone  used  shall  generally  be  from 
three-fourths  of  a  cubic  foot  to  2  cubic  feet  in  volume. 

Measurement.  All  masonry  shall  be  built  according  to  the 
plans  and  instructions  furnished  by  the  Engineer,  and  the  several 
classes  thereof  shall  be  estimated  and  paid  for  by  the  cubic  yard, 
computing  only  the  actual  solidity  thereof  required  by  the  plans. 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  39 

No  constructive  or  conventional  measurement  shall  be  allowed, 
any  rule  or  custom  to  the  contrary  notwithstanding. 

Freezing  Weather.  All  work  in  stone  and  brick  masonry  and 
concrete  shall  be  suspended  during  freezing  weather  except  on 
structures  in  which  delay  would  affect  the  general  progress  of 
the  work  and  under  such  regulations  and  conditions  as  the  Engi- 
neer may  prescribe.  Whenever  required  by  the  Engineer,  the 
sand  and  water  shall  be  heated  before  being  used  in  the  work. 
No  masonry  laid  in  freezing  weather  shall  be  pointed  until  spring. 

Inspection.  All  material  shall  be  subject  to  inspection  and 
any  that  has  been  condemned  shall  immediately  be  removed  from 
the  site  of  the  work.  All  masonry  shall  be  subject  to  the  super- 
vision of  an  Inspector  whose  duties  shall  be  to  see  that  the  re- 
quirements of  these  specifications  are  conformed  to,  but  his  pres- 
ence is  in  no  way  to  be  presumed  to  lessen  in  any  degree  the 
responsibility  of  the  Contractor  or  his  obligations. 

No  masonry  of  any  kind  shall  be  covered  up  before  it  has 
been  inspected  and  passed  upon. 

Price  to  Include.  The  price  per  cubic  yard  paid  for  stone, 
brick,  or  concrete  masonry  shall  include  the  furnishing  of  all 
material,  all  scaffolding,  forms,  and  centering,  and  all  other  ex- 
penses necessary  to  the  construction  and  completion  of  the 
masonry  and  the  maintenance  of  same  until  the  work  is  accepted. 

CLASSIFICATION  OF  MASONRY 

Masonry  shall  be  classified  under  the  following  heads:  First 
Class;  Second  Class;  Third  Class;  First-Class  Arch;  Brick;  and 
Concrete. 

First=Class  Masonry 

First-class  masonry  shall  consist  of  range  rock  work  of  the 
best  description.  The  face  stones  shall  be  accurately  squared, 
pointed,  and  bedded,  and  laid  in  regular  and  horizontal  courses 
of  not  less  than  12  inches  in  thickness  and  not  greater  than  30 
inches,  decreasing  in  thickness  regularly  from  the  bottom  to  the 
top  of  the  walls.  The  stones  of  each  course  shall  be  so  arranged 
as  to  form  a  proper  bond  with  the  stones  of  the  underlying 
courses,  and  a  bond  of  less  than  1  foot  shall  in  no  case  be  allowed. 

Stretchers.  Stretchers  shall  not  be  less  than  4  feet  in  length. 
They  shall  have  18  inches  width  of  bed  for  all  courses  under  18 
inches;  and  for  all  courses  above  18  inches  they  shall  have  as 
much  bed  as  face.  They  shall  not  break  joint  on  headers. 

Headers.  Headers  shall  not  be  less  than  4  feet  in  length. 
They  shall  occupy  one-fifth  of  the  face  of  the  wall  and  no  header 
shall  have  less  than  18  inches  width  of  face;  where  the  course 


359 


40  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

exceeds  18  inches  in  height,  the  width  of  face  shall  not  be  less 
than  the  height  of  the  course. 

When  the  walls  do  not  exceed  4  feet  in  thickness,  the  headers 
shall  run  entirely  through,  and  in  all  cases  they  shall  be  long 
enough  to  form  a  proper  bond  with  the  backing. 

When  the  stone  used  in  any  work  is  in  very  large  blocks,  ex- 
ceeding the  requirements  given  above,  then  a  stone  that  runs 
into  the  wall  to  a  distance  at  least  as  great  as  the  average  length 
of  the  stretchers  shall  be  considered  a  header. 

Backing.  The  backings  shall  be  of  third-class  masonry  or 
1-3-6  concrete,  as  shall  be  directed  by  the  Engineer,  well  bonded 
with  the  facework  and  itself. 

Foundation  Courses.  All  work  below  the  neat  line  shall  be 
1-3-6  concrete,  laid  as  specified,  and  paid  for  at  the  price  for 
"1-3-6  concrete  masonry  in  foundation". 

Laying.  The  masonry  shall  be  -  laid  up  as  specified  under 
"Laying". 

Bridge  Piers.  Bridge  piers  built  in  streams  subject  to  ice 
floes  shall  be  built  of  first-class  masonry  facing  with  concrete 
masonry  backing,  in  the  heart  of  the  wall. 

The  stones  forming  the  cutwater  of  piers  which  act  as  ice 
breakers  shall  be  neatly  and  smoothly  dressed  on  their  faces,  and 
fastened  together  with  iron  cramps  and  to  the  interior  of  the 
piers.  The  surfaces  of  the  other  face  stones  shall,  with  the  ex- 
ception of  the  draft,  be  left  as  they  come  from  the  quarry  unless 
the  projection  above  the  draft  exceeds  3  inches,  in  which  ease 
they  shall  be  roughly  scabbled  down  to  that  projection. 

Second=Class   Masonry 

Second-class  masonry  shall  consist  of  broken  or  random  range 
rock  work  of  the  best  description,  and  shall  conform  in  every 
other  respect  to  first-class  masonry. 

Third-Class  Masonry 

Third-class  masonry  shall  be  formed  of  approved  quarry  stone 
of  good  shape  and  good  flat  beds.  No  stones  shall  be  used  in 
the  face  of  the  walls  less  than  6  inches  thick,  or  less  than  12 
inches  in  their  least  horizontal  dimensions. 

Headers  and  Face  Stones.  Headers  shall  generally  form  at 
least  one-fifth  of  the  faces  and  backs  of  the  walls,  with  a  similar 
proportion  throughout  the  mass  when  they  do  not  interlock,  and 
the  face  stones  shall  be  well  scabbled  or  otherwise  worked  so 
that  they  may  be  set  close,  and  chinking  with  small  stones  be 
avoided. 


260 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  41 

Size  of  Stones,  etc.  In  walls  5  feet  thick  or  less,  the  stones 
used  shall  average  from  6  to  8  cubic  feet  in  volume,  and  the 
length  of  the  headers  shall  be  equal  to  two-thirds  of  the  thickness 
of  the  wall ;  in  walls  over  5  feet  in  thickness,  the  stones  used  shall 
average  12  cubic  feet  in  volume,  and  the  headers  shall  not  be  less 
than  4  feet  long.  Generally  no  stones  shall  be  used  having  a 
less  volume  than  4  cubic  feet,  except  for  filling  the  interstices 
between  the  larger  stones. 

Limit  of  Height  and  Bond.  In  no  case  shall  stones  be  used 
having  a  greater  height  or  build  than  30  inches,  and  these  stones 
must  bond  the  joints  above  and  below  at  least  18  inches;  in  all 
other  cases  the  smaller  stones  used  must  bond  the  joints  above 
and  below  at  least  10  inches. 

Foundation  Stones.  The  stones  in  the  foundation  generally 
shall  be  not  less  than  10  inches  in  thickness  and  contain  not  less 
than  10  square  feet  of  surface. 

The  foundation  shall  consist  of  1-3-6  concrete,  if  so  directed 
by  the  Engineer. 

Laying.  The  masonry  shall  be  laid  up  as  specified  under 
"Laying". 

First=CIass  Arch   Masonry 

First-class  arch  masonry  shall  be  laid  in  cement  mortar,  and 
shall  be  built  in  accordance  with  the  specifications  for  first-class 
masonry,  when  and  to  the  extent  that  the  Engineer  may  direct. 
The  ring  stones  shall  be  dressed  to  such  size  and  shape  as  the 
Engineer  may  determine. 

Ring  Stones  and  Arch-Sheeting  Stones.  The  ring  stones  and 
arch-sheeting  stones  shall  not  be  of  less  thickness  than  10  inches 
on  the  intrados  of  the  arch,  and  shall  be  dressed  with  §-inch 
radial  joints,  and  shall  be  of  the  full  depth  specified  by  plans, 
or  otherwise,  for  the  thickness  of  the  arch.  The  joints  shall  be 
made  on  true  radial  lines,  and  the  ends  of  the  sheeting  stones 
and  the  ring  stones  shall  be  dressed  to  make  close  joints.  The 
ring  stones  and  the  arch-sheeting  stones  shall  break  joints  not 
less  than  1  foot  apart. 

Parapets.  The  parapets  shall  be  finished  with  a  coping  course 
of  the  full  width  of  the  top  of  the  parapet,  with  such  projection 
as  may  be  directed  by  the  Engineer.  The  stones  shall  be  not  less 
than  10  inches  in  thickness. 

Brick  Masonry 

Brick  masonry  shall  be  laid  with  the  best  quality  of  hard 
burned  brick,  well  tempered  and  molded  to  standard  size. 


361 


42  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Quality  of  Bricks.  No  bats,  except  necessarily  as  closers  for 
properly  dimensioning  the  several  courses,  nor  cracked,  crooked, 
or  salmon  bricks,  shall,  under  any  circumstances,  be  allowed  in 
the  work.  The  bricks  shall  be  thoroughly  wetted  and  shall  be 
laid,  end  and  side  at  one  operation,  in  full  close  joints  of  mortar. 
The  style  of  bond  shall  be  prescribed  by  the  Engineer.  The  best- 
shaped  and  best-colored  brick  shall  be  reserved  for  facework, 
which  shall  be  finished  with  a  neatly  drawn  joint  and  pointed 
where  required. 

Mortar  and  Grouting.  Proportions.  All  mortar  to  be  used  in 
the  building  of  stone  or  brick  masonry  shall  be  composed  of  1 
part  of  cement  to  3  parts  of  sand.  All  mortar  for  pointing  and 
bedding  copings,  bridge  seats,  and  pedestal  blocks  shall  be  com- 
posed of  1  part  of  cement  to  2  parts  of  sand. 

Grout  shall  be  composed  of  1  part  of  Portland  cement  to  3 
parts  of  sand,  except  where  the  foundations  are  wet,  when  the 
quantity  of  sand  shall  be  diminished,  making  the  proportions  1 
part  of  cement  to  2  parts  of  sand,  and  this  shall  be  used  in  the 
foundation  masonry  up  to  the  neat  lines,  if  required. 

All  the  above  mixtures  shall  be  proportioned  by  measurement. 
It  is  assumed  that  376  pounds  of  cement  shall  have  a  volume  of 
3.6  cubic  feet.  The  sand  and  cement  shall  first  be  mixed  dry  in 
suitable  tight  boxes,  after  which  the  proper  amount  of  water 
shall  be  gradually  added.  Only  such  quantities  of  mortar  or 
grouting  shall  be  mixed  as  are  needed  for  immediate  use;  if 
allowed  to  set,  it  shall  not  be  retempered  and  used  in  masonry 
construction. 

Tensile  Strength.  Mortar  taken  from  the  mixing  box  and 
molded  into  briquettes,  1  square  inch  in  cross  section,  shall 
develop  the  following  ultimate  tensile  strengths: 

PER  SQUARE  INCH 
7  days  (1  day  in  air,  6  days  in  water),  1  part 

of  cement  to  3  parts  of  sand 125  Ibs. 

28  days  (1  day  in  air,  27  days  in  water),  1 

part  of  cement  to  3  parts  sand 175  Ibs. 

Sand.  Sand  for  grouting"  shall  be  tide-washed,  sharp,  siliceous, 
dry-screened  bar  or  approved  bank  sand,  containing  not  more 
than  5  per  cent  of  loam,  clay,  dirt,  or  other  impurities.  Sand  for 
mortar  shall  be  composed  of  grains  graded  from  coarse  to  fine, 
thoroughly  screened  to  reject  all  particles  exceeding  one-eighth 
inch  in  diameter,  and  shall  be  clean  and  sharp,  containing  not  more 
than  5  per  cent  by  weight  of  clay,  loam,  dirt  and  other  impurities, 
and  equal  in  quality  to  the  best  New  Jersey  bank  sand. 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  43 

Water.  Water  shall  be  fresh,  and  free  from  dirt,  oil,  or  grease. 
Salt  water  may  be  used,  as  directed  by  the  Engineer,  when  nec- 
essary to  construct  masonry  in  freezing  weather. 

Cement 

Kind.  All  cement  shall  be  Portland,  of  the  best  quality,  dry 
and  free  from  lumps.  By  Portland  cement  is  meant  the  finely- 
pulverized  product  resulting  from  the  calcination  to  incipient 
fusion  of  an  intimate  mixture  of  properly  proportioned  argilla- 
ceous and  calcareous  materials  to  which  no  addition  greater  than 
3  per  cent  has  been  made  subsequent  to  calcination. 

Packages.  Cement  shall  be  packed  in  strong  cloth  or  canvas 
bags,  or  in  sound  barrels  lined  with  paper,  which  shall  be  plainly 
marked  with  the  brand  and  name  of  the  manufacturer.  Bags 
shall  contain  94  pounds  net  and  barrels  shall  contain  376  pounds 
net. 

Inspection.  All  cement  shall  be  inspected.  The  Contractor 
shall  submit  the  cement,  and  afford  every  facility  for  inspection 
and  testing,  at  least  12  days  before  desiring  to  use  it.  The  Engi- 
neer shall  be  notified  at  once  upon  receipt  of  each  shipment.  No 
cement  shall  be  inspected  or  allowed  to  be  used  unless  delivered 
in  suitable  packages,  properly  branded. 

Protection.  The  cement  shall  be  protected  in  a  suitable  build- 
ing having  a  wTooden  floor  or  platform  raised  from  the  ground, 
and  may  be  reinspected  at  any  time. 

Storage.  The  cement  shall  be  stored  in  a  manner  that  will 
enable  each  carload  lot  to  be  kept  separate  and  be  tagged  with 
car  number  and  date  of  receipt.  One  carload  shall  not  be  placed 
immediately  upon  another. 

Failure  of  Brand.  The  failure  of  a  shipment  of  cement  on 
any  work  to  meet  the  requirements  given  below  may  prohibit 
further  use  of  the  same  brand  on  that  work.  Rejected  cement 
shall  immediately  be  removed  from  the  work. 

Quality.  The  acceptance  or  rejection  of  a  cement  to  be  used 
shall  rest  with  the  Engineer,  and  shall  be  based  on  the  following 
requirements : 

Specific  Gravity:  not  less  than  3.1. 
Ultimate  Tensile  Strength  per  square  inch: 

1  days  (1  day  in  air,  6  days  in  water) 500  Ibs. 

28  days  (1  day  in  air,  27  days  in  water) . .   600  Ibs. 
7  days  (1  day  in  air,  6  days  in  water),  1 
part   of   cement   to   3   parts   standard 
quartz  sand 200  Ibs. 


44  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

28  days  (1  day  in  air,  27  days  in  water),  1 
part  of  cement  to  3  parts  standard 
quartz  sand 275  Ibs. 

Fineness:  Residue  on  No.  100  sieve  not  over  8  per  cent  by  weight. 
Residue  on  No.  200  sieve  not  over  25  per  cent  by 
weight. 

Set.  It  shall  require  at  least  30  minutes  to  develop  initial  set, 
and  not  less  than  1  hour  nor  more  than  10  hours  to  develop  hard 
set.  These  requirements  may  be  modified  where  the  conditions 
of  use  make  it  desirable. 

Constancy  of  Volume.  Pats  of  cement  3  inches  in  diameter, 
one-half  inch  thick  at  center,  and  tapering  to  a  thin  edge,  when 
immersed  in  water  after  24  hours  in  moist  air,  shall  show  no  signs 
of  cracking,  distortion,  or  disintegration.  Similar  pats  in  air 
shall  also  remain  sound  and  hard.  The  cement  shall  pass  such 
accelerated  tests  as  the  Engineer  may  determine. 

The  following  test  will  be  made  in  accordance  with  the  rules 
adopted  for  Standard  tests  by  the  American  Society  for  Testing 
Materials,  August  16,  1909,  with  subsequent  amendments. 

Sulphuric  anhydride  (S03)  ;  not  more  than  1.75 
per  cent. 

Magnesia  (MgO)  ;  not  more  than  4  per  cent. 

Briquettes  for  testing  shall  be  1  square  inch  in 
area  of  cross  section;  sieves  shall  be  of  brass  wire- 
cloth  having  approximately  9800  and  37,500  meshes 
per  square  inch,  respectively,  the  diameter  of  the 
wire  being  0.0045  and  0.0023  inches,  respectively. 

Concrete 

Proportions.  Concrete  masonry  shall  consist  of  two  grades. 
These  shall  be  used  wherever  specified  or  directed  by  the 
Engineer.  They  shall  be  known  as  1-2-4  and  1-3-6,  respectively. 

Parts  by  Volume 


CEMENT 

SAND 

STONE 

1 

2 

4 

1 

3 

6 

If  required  by  the  Engineer,  the  mixture  shall  be  modified 
by  changing  the  relative  amounts  of  sand  and  stone,  but  keeping 
the  aggregate  of  6  parts  of  sand  and  stone  for  the  1-2-4  concrete, 
and  9  parts  of  sand  and  stone  for  the  1-3-6  concrete. 


264 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  45 

The  proportions  of  all  materials  shall  be  determined  by  meas- 
urement. The  volume  of  a  barrel  of  cement,  376  pounds,  shall 
be  assumed  to  be  3.6  cubic  feet.  The  sand  and  stone  shall  not 
be  packed  more  closely  than  by  throwing  in  the  usual  way  into 
a  barrel  or  box  at  the  time  of  measurement. 

Cement.  Portland  cement  shall  be  used,  of  the  quality  speci- 
fied under  "Cement". 

Stone.  The  stone  shall  be  clean  hard  crushed  stone  or  peb- 
bles, to  be  approved  by  the  Engineer,  composing  the  whole  run 
of  the  crusher,  in  size  from  one-fourth  inch  to  three-fourths  inch, 
when  used  for  bedding  on  metal  decks,  bridge  seats,  etc.;  and 
from  one-fourth  inch  to  1^  inches  for  other  purposes,  screened 
of  dust  and  particles  less  than  one-fourth  inch. 

Sand.  Sand  shall  be  clean  and  sharp  and  shall  be  composed 
of  grains  graded  from  fine  to  coarse,  screened  if  required,  to 
reject  all  particles  of  a  greater  diameter  than  one-fourth  inch. 
It  shall  not  contain  more  than  a  5  per  cent  weight  of  clay,  loam, 
dirt,  or  other  impurities,  and  shall  be  equal  in  quality  to  the 
best  New  Jersey  bank  sand. 

Care  of  Sand  and  Stone.  Sand  and  stone  when  delivered  on 
the  work  shall  be  dumped  on  platforms  and  not  upon  the  ground. 

Machine  Mixing.  All  mixing  shall  preferably  be  done  by 
machine,  but  hand  mixing  shall  be  allowed  in  special  cases. 

"When  mixed  by  machine,  cubical  box  mixers,  or  those  which 
allow  of  dry  mixing  of  the  materials  before  the  water  is  added, 
shall  be  preferred.  The  proportions  shall  be  accurately  deter- 
mined before  being  placed  in  the  mixer  and  means  shall  be  pro- 
vided for  accurately  measuring  the  water. 

(See  water  specifications,  page  43.) 

Measuring  boxes  or  other  approved  apparatus  shall  be  used, 
so  that  the  proportions  can  be  exactly  determined.  The  ingredi- 
ents shall  be  thoroughly  mixed  before  the  water  is  added,  and 
the  mixing  shall  be  continued  until  every  particle  of  stone  is 
covered  with  mortar.  No  retempering  shall  be  allowed  under 
any  conditions. 

Hand  Mixing.  When  mixed  by  hand,  the  cement  and  sand 
shall  be  first  mixed  dry  and  then  made  into  a  mortar.  The  stone 
shall  be  spread  upon  a  suitable  floor  to  a  depth  of  about  6  inches 
and  thoroughly  wetted  (see  water  specifications,  page  43),  and 
the  mortar  evenly  spread  over  it,  care  being  taken  that  the  stone 
of  each  batch  is  mixed  as  to  size.  The  whole  mass  shall  then 
be  turned  over  4  times  and  raked  to  secure  complete  and  uniform 
mixture.  If  the  Contractor  desires  to  use  some  other  method, 
he  shall  submit  it  for  approval.  Should  the  mixture  be  per- 
mitted to  set  before  placing  or  tamping,  it  shall  be  removed  and 


265 


46  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

not  used.  Hand-mixed  batches  shall  not  be  larger  than  1  cubic 
yard  in  volume. 

Depositing.  All  concrete  shall  be  deposited  in  sections  and 
in  layers  of  such  thickness  —  not  exceeding  9  inches  —  as  the 
Engineer  shall  direct.  It  shall  be  of  such  consistency  that  when 
dumped  in  place  it  will  not  require  much  tamping,  but  shall  not 
be  wet  enough  to  cause  the  mortar  to  separate  from  the  stone; 
it  shall  be  spaded  down  and  tamped  sufficiently  to  level  off  and 
will  then  quake  freely  like  jelly.  Where  concrete  is  marked  on 
the  face  into  courses,  each  requiring  two  or  more  layers,  the 
layers  shall  follow  each  other  in  close  succession  before  setting, 
so  as  to  avoid  visible  joints  on  the  face  of  a  course. 

Surface  of  Concrete  Exposed  to  the  Street.  Surfaces  of  con- 
crete exposed  to  the  street  shall  be  composed  of  1  part  cement,  2 
parts  coarse  sand  or  gravel,  and  2  parts  granolithic  grit,  made 
into  a  stiff  mortar.  Granolithic  grit  shall  be  granite  or  trap 
rock  crushed  to  pass  a  one-fourth-inch  sieve  and  screened  of  dust. 
For  vertical  surfaces  the  mixture  shall  be  deposited  to  a  minimum 
thickness  of  1  inch  against  the  face  forms  by  skilled  workmen. 
This  shall  be  done  as  the  placing  of  the  concrete  proceeds,  and  thus 
form  a  part  of  the  body  of  the  work.  Care  shall  be  taken  to 
prevent  the  occurrence  of  air  spaces  or  voids  in  the  surface.  The 
face  forms  shall  be  removed  as  soon  as  the  concrete  has  suffi- 
ciently hardened  and  any  voids  that  may  appear  shall  be  filled 
up  with  the  mixture. 

The  surface  shall  then  be  washed  immediately  with  water 
until  the  grit  is  exposed ;  it  shall  then  be  rinsed  clean,  protected 
from  the  sun,  and  kept  moist  for  3  days.  For  horizontal  surfaces, 
the  granolithic  mixture  shall  be  deposited  on  the  concrete  to  a 
minimum  thickness  of  1J  inches,  immediately  after  the  concrete  has 
been  tamped  and  before  it  has  set,  and  shall  be  troweled  to  an 
even  surface ;  after  it  has  set  sufficiently  hard,  it  shall  be  washed 
until  the  grit  is  exposed. 

All  concrete  surfaces  exposed  to  the  street  shall  be  marked 
off  into  courses  in  such  detailed  manner  as  may  be  directed  by 
the  Engineer. 

Other  Showing  Surfaces.  All  other  showing  surfaces  shall  be 
prepared  by  keeping  the  stone  well  back  from  the  face  as  the 
concrete  is  placed;  this  is  done  by  bringing  the  mortar  against 
the  forms  by  "spading". 

Horizontal  exposed  surfaces  shall  be  finished  with  a  layer  of 
cement  mortar,  1  part  cement  to  2  parts  sand,  1  inch  thick,  and 
troweled  to  a  smooth  surface. 

After  the  forms  are  removed  the  surfaces  shall  be  pointed 


266 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  47 

where  necessary  and  washed  with  neat  cement  applied  with  a 
brush. 

Plastering  the  face  after  removing  the  forms  shall  not  be 
permitted. 

Protection  of  Exposed  Surfaces.  Provision  shall  be  made  to 
protect  exposed  surfaces  from  the  action  of  the  elements,  until 
the  concrete  has  set. 

Forms.  Suitable  forms  shall  be  constructed,  the  cost  of  which 
shall  be  included  in  the  price  per  cubic  yard  for  the  concrete. 

The  dimensions  shall  be  such  that  the  finished  concrete  shall 
be  of  the  form  and  dimensions  shown  on  the  plans  or  as  ordered 
by  the  Engineer.  All  forms  shall  be  set  true  to  the  lines  desig- 
nated and  shall  be  built  so  as  to  remain  firm  and  secure  until 
the  concrete  has  firmly  set.  They  shall  be  satisfactory  to  the 
Engineer  and  shall  remain  in  place  as  long  as  he  deems  it  neces- 
sary. The  interior  surfaces  of  the  forms  which  come  in  contact 
with  the  exposed  surfaces  of  the  concrete  shall  be  of  dressed 
lumber  having  close  joints,  and  shall  be  so  constructed  as  to 
leave  all  exposed  surfaces  of  the  concrete  smooth,  even,  and  pre- 
sentable. Face  forms  shall  have  triangular  beads  secured  to  the 
planks  to  mark  the  face  of  the  concrete  into  courses  by  imprint. 

All  top  edges  of  copings,  pedestal  blocks,  and  bridge  seats, 
the  vertical  angles  of  abutments,  piers,  and  retaining  walls,  and 
the  bottom  edges  of  the  rings  of  all  arches  shall  be  formed  by 
placing  fillets  inside  the  forms  as  shown  on  the  plans. 

Cleaning  Joints.  In  work  above  ground,  the  top  surface  of 
each  course  shall  be  scraped  within  24  hours,  to  remove  the 
"laitance"  or  scum,  and  insure  the  adhesion  of  the  next  layer. 

Contraction  Joints.  Contraction  joints  shall  be  placed  wher- 
ever directed  by  the  Engineer.  The  sections  of  wall  shall  gen- 
erally be  about  50  feet  in  length,  shall  be  made  with  tongue  and 
grooved  joints  as  directed,  and  corrugated  asbestos  boards  shall 
be  used  on  the  faces  of  the  joints.  Payment  shall  be  made  for 
the  corrugated  asbestos  boards  at  the  price  given  in  the  proposal, 
but  all  other  expenses  attendant  upon  making  the  joint  shall  be 
included  in  the  price  per  cubic  yard  of  concrete. 

Steel  in  Reinforcement.  Rods  for  reinforcing  concrete  shall 
be  of  steel  of  some  approved  shape  specially  formed  for  that 
purpose  and  designed  to  secure  an  interlocking  bond  between 
the  concrete  and  the  steel.  If  the  rods  are  twisted,  the  twists 
shall  be  made  cold  and  shall  be  sufficient  to  give  one  complete 
turn  in  a  length  equal  to  6  times  the  least  diameter  of  the  bar. 

Imbedded  Stone.  If  the  Contractor  shall  so  elect,  approved 
hard  stone  not  exceeding  6  to  8  feet  may  be  imbedded  in  the 
foundation  concrete;  similar  stone,  but  not  larger  than  2  cubic 


267 


48  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

feet  each,  may  be  imbedded  in  the  neat  work.  The  stones  shall 
be  thoroughly  cleaned  and  placed  so  as  to  be  entirely  surrounded 
by  concrete,  and  shall  not  be  closer  than  6  inches  to  any  face  of 
the  work.  In  the  neat  work,  the  stones  shall  be  imbedded  so  as 
to  form  dowels  bonding  each  day's  work. 

Concrete  Deposited  under  Water.  In  case  it  is  found  neces- 
sary to  lay  concrete  under  water,  approved  appliances  shall  be 
used  to  insure  its  being  deposited  with  as  little  injury  as  possible. 

Waterproofing 

Percolation  of  Water  to  be  Prevented.  It  is  the  very  essence 
of  these  specifications  to  secure  an  underground  structure  which 
shall  be  entirely  free  from  the  percolation  of  ground  water  or 
outside  water,  to  which  end  construction  shall  be  carried  out 
as  follows : 

Preparation  of  Foundations.  After  the  soil  has  been  exca- 
vated to  the  required  depth  and  dressed  off  to  a  true  grade  as 
directed  by  the  Engineer,  there  shall  be  laid  a  bed  of  concrete 
of  the  proportions  herein  described,  and  of  such  thickness  as  (in 
the  judgment  of  the  Engineer)  the  local  conditions  demand.  On 
such  bed,  which  shall  be  made  as  level  and  smooth  as  possible 
on  the  top  surface,  there  shall  be  spread  a  layer  of  hot  asphalt, 
and  on  such  asphalt  there  shall  be  immediately  laid  sheets  or 
rolls  Of  felt,  all  of  the  quality  hereinafter  described ;  another  layer 
of  hot  asphalt  shall  be  spread  over  the  felt;  another  layer  of 
felt  laid,  and  so  on  until  not  less  than  2  such  layers  of  felt 
nor  more  than  6  be  laid,  with  asphalt  between  each  layer,  and 
asphalt  beneath  and  on  top  of  the  whole.  On  top  of  the  upper 
surface  of  asphalt,  the  remainder  of  the  concrete  as  called  for 
by  the  contract  drawings  shall  be  put  in  place.  In  dry  open  soil 
the  felt  in  the  floor  concrete  may  be  omitted,  the  base  course  of 
concrete  being  covered  with  one  good  layer  of  asphalt.  In  rock 
excavation,  where  the  same  is  dry  and  above  water  level,  both 
the  felt  and  the  asphalt  in  the  floor  may  be  omitted. 

Side-Wall  Construction.  When  the  I-beam  columns  of  the 
side  walls  are  set  and  secured  permanently  in  place,  the  concrete 
composing  the  side  walls  shall  be  rammed  in  place  in  such  manner 
that  the  back  or  outer  face  is  flush  with  the  outer  flanges  of  the 
columns.  On  such  outer  face  hot  asphalt  shall  be  brushed  and 
felt  spread  in  alternate  layers,  in  the  same  manner  as  described 
for  the  foundations,  and  the  backing  of  concrete  shall  then  be 
added,  as  shown  by  the  plans.  Instead  of  constructing  the  side 
walls  with  the  waterproofing  as  described  above,  the  Contractor 
may  build  in  dry  open  soils,  if  permitted  by  the  Engineer  and  if 


268 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  49 

110  additional  width  of  excavation  is  required  for  sewers  or  other 
purposes,  a  4-inch  brick  wall  supported  at  the  back  by  the  trench 
sheathing,  laid  in  cement  mortar  or  hot  asphalt,  and  at  a  distance 
of  at  least  2  inches  in  the  clear  from  the  line  of  the  exterior  faces 
of  the  side-wall  beams ;  and  then  he  may  attach  to  ft  the  layers 
of  waterproofing  material  as  described  above,  and  ram  around  the 
beams  and  against  the  waterproofing  surface  the  concrete  com- 
posing the  side  walls.  Under  similar  conditions  in  dry  rock 
excavation,  the  rock  may  be  excavated  so  that  no  projecting 
point  comes  within  3  inches  of  the  line  of  the  exterior  face  of  the 
side-wall  beams;  then  the  rough  surface  shall  be  made  smooth 
with  a  plaster  of  concrete,  and  on  such  smooth  surface  the  water- 
proofing material  shall  be  spread;  and  then  the  concrete  of  the 
side  walls  may  be  rammed  against  the  same  in  the  manner 
described  above. 

Roof  Construction.  The  roof  of  the  structure  shall  be  treated 
in  a  similar  manner  by  finishing  the  jack  arches  to  such  height  as 
may  be  directed  by  the  Engineer,  spreading  the  asphalt  and  felt 
in  alternate  layers,  and  then  adding  a  cover  of  concrete,  complet- 
ing the  roof  as  called  for  by  the  Contract  Drawings. 

Continuous  Waterproof  Envelope.  By  the  arrangement  above 
described  there  will  be  a  continuous  sheet  of  asphalt  and  felt 
imbedded  within  the  concrete  of  the  bottom,  top,  and  both  sides, 
and  completely  enveloping  the  structure. 

Quality  of  Asphalt.  The  asphalt  used  shall  be  the  best  grade 
of  Bermudez,  Alcatraz,  or  lake  asphalt  of  equal  quality,  and  shall 
comply  with  the  following  requirements: 

The  asphalt  shall  be  a  natural  asphalt  or  a  mix- 
ture of  natural  asphalts,  containing  in  its  refined 
state  not  less  than  95  per  cent  of  natural  bitumen 
soluble  in  rectified  carbon  bisulphide  or  in  chloro- 
form. The  remaining  ingredients  shall  be  such  as 
not  to  exert  an  injurious  effect  on  the  work.  Not 
less  than  two-thirds  of  the  total  bitumen  shall  be 
soluble  in  petroleum  naphtha  of  70°  Baume  or  in 
acetone.  The  asphalt  shall  not  lose  more  than  4  per 
cent  of  its  weight  when  maintained  for  10  hours  at  a 
temperature  of  300°  Fahrenheit. 

Coal  Tar  Prohibited.  The  use  of  coal  tar,  so-called  artificial 
asphalts,  or  other  products  susceptible  to  injury  from  the  action 
of  water,  will  not  be  permitted  on  any  portion  of  the  work,  or  in 
any  mixtures  to  be  used. 

Quality  of  Felt.  The  felt  used  in  waterproofing  such  part  of 
the  structure  as  is  below  ground  water  level  shall  be  composed 


50  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

of  asbestos  or  other  equally  nonperishable  material  dipped  in 
asphalt  and  weighing  not  less  than  10  pounds  to  the  square  of 
100  feet.  The  felt  used  in  other  parts  of  the  structure  shall  be 
the  same  as  the  above,  or  of  the  best  quality  of  coal  tar  felt 
weighing  not  less  than  15  pounds  to  the  square  of  100  feet ;  except 
that,  if  the  latter  be  used,  one  layer  more  of  it  will  be  required 
than  of  the  former.  All  felt  shall  be  subject  to  the  approval  of 
the  Engineer. 

Surfaces  to  be  Smooth.  The  surfaces  to  be  waterproofed  shall 
be  smooth,  without  projecting  stones,  or  made  smooth  where 
necessary  by  a  coating  of  mortar  made  of  one  portion  Natural 
cement  to  one  portion  sand,  and  should  be  dry  before  the  asphalt 
is  applied. 

Artificial  Drying.  Means  for  artificially  drying  the  surface 
of  concrete  may  be  taken  by  the  Contractor  by  blowing  warm  air 
over  it,  or  as  otherwise  permitted  by  the  Engineer,  but  not  until 
the  concrete  has  had  at  least  48  hours  in  which  to  set. 

No  Cracks  or  Blowholes.  Each  layer  of  asphalt  fluxed  as 
directed  by  the  Engineer  must  completely  and  entirely  cover  the 
surface  on  which  it  is  spread,  without  cracks  or  blowholes. 

Felt  to  be  Carefully  Laid.  The  felt  must  be  rolled  out  into 
the  asphalt  while  the  latter  is  still  hot,  and  pressed  against  it  so 
as  to  insure  its  being  completely  stuck  to  the  asphalt  over  its 
entire  surface.  Great  care  should  be  taken  that  all  joints  in  the 
felt  are  well  broken ;  that  the  ends  of  the  rolls  of  the  bottom  layer 
be  carried  up  on  the  inside  of  the  layers  on  the  sides;  and  that 
those  of  the  roof  be  carried  down  on  the  outside  of  the  layers  on 
the  sides,  so  as  to  secure  a  full  lap  of  at  least  3  feet.  Especial 
care  must  be  taken  with  this  detail. 

Skilled  Men.  None  but  competent  men,  especially  skilled  in 
work  of  this  kind,  shall  be  employed  to  lay  asphalt  and  felt. 

Top  Surface  of  Asphalt  not  to  be  Broken.  When  the  finishing 
layer  of  concrete  is  laid  over  or  next  to  the  waterproofing 
material,  care  must  be  taken  not  to  break,  tear,  or  injure  in  any 
way  the  outer  surface  of  the  asphalt. 

Number  of  Layers  of  Felt.  The  number  of  layers  of  felt  on 
the  sides  and  under  the  floor  shall  in  no  case  be  less  than  2  in 
ground  that  is  quite  dry;  and  where  there  is  a  water  pressure 
against  the  masonry  equal  to  12  feet,  there  shall  not  be  less  than 
6  layers.  Where  the  water  pressure  is  less  than  12  feet,  or  where 
the  ground  is  damp,  such  number  of  layers  between  3  and  6  shall 
be  used  as  the  Engineer  may  direct.  The  number  of  layers  of 
felt  on  the  roof  shall  be  not  less  than  3  of  asphalted  asbestos  or  4 
of  tarred  felt. 

Bricks  Dipped  in  Asphalt.     At  any  point  where  the  Contract 


270 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  51 

Drawings  and  the  Engineer  permit,  the  Contractor  may  lay, 
instead  of  the  asphalt  and  felt  above  described,  one  or  more 
courses  of  bricks  dipped  in  hot  asphalt  of  the  above  described 
quality,  and  laid  while  the  coating  of  asphalt  is  still  hot. 

Asphaltic  Concrete.  In  foundations,  the  Contractor  may  lay, 
if  he  prefer,  instead  of  the  ordinary  concrete  with  the  layer  of 
waterproofing  material,  as  above  described,  a  bed  of  asphaltic 
concrete,  composed  of  broken  stone  of  the  qualities  previously 
described  for  concrete,  heated  in  a  suitable  heater  to  such  proper 
temperature  as  the  Engineer  may  direct  and,  when  so  heated, 
have  added  thereto  the  melted  asphalt  of  the  quality  as  described 
above,  in  such  proportion  as  to  insure  a  covering  of  each  particle 
of  stone  with  asphalt;  the  whole  mass  shall  then  be  thoroughly 
mixed  and  incorporated  in  a  suitable  mixer.  Such  asphaltic  con- 
crete shall  be  spread  in  place  and  thoroughly  rolled  and  com- 
pressed, so  that  it  will  present  a  smooth  even  surface  that  will 
be  impervious  to  water.  No  asphalt  shall  be  heated  to  exceed  a 
temperature  of  325°  Fahrenheit. 

Waterproofing — When  Omitted.  In  masonry-lined  structures 
where  there  is  no  steel  work  and  the  ground  is  dry,  the  regular 
waterproofing  may  be  omitted,  but  in  that  case  in  arched-cut  and 
cover  work  the  extrados  of  the  arch  shall  be  coated  with  hot 
asphalt  of  the  quality  described,  or  the  best  grade  of  refined 
Trinidad  asphalt. 

Leaky  Masonry  to  be  Rebuilt.  Any  masonry  that  is  found  to 
leak  at  any  time  prior  to  the  completion  of  this  work  shall  be 
cut  out  and  the  leak  stopped,  if  so  ordered  by  the  Engineer. 

LUMBER 

Specifications.  All  lumber  shall  be  sound,  straight  grained, 
and  free  from  excessive  sap,  loose  or  rotten  knots,  wind  shakes, 
or  any  other  defect  that  would  impair  its  strength  or  durability. 
It  shall  be  sawed  or  hewed  perfectly  straight  to  exact  dimensions, 
with  full  corners  and  square  edges. 

All  long-leaf  yellow  pine  shall  be  first-class  Southern  long- 
leaf  yellow  pine,  sawed  true  and  out  of  wind,  full  size,  free  from 
wind  shakes,  large  or  loose  knots,  or  other  defects  impairing  its 
strength  or  durability,  and  equal  in  quality  to  the  grade  of 
*  in  ''Interstate  Rules  of  1905,  for  Classifi- 
cation and  Inspection  of  Yellow  Pine  Lumber". 

All  framing  shall  be  done  in  a  thoroughly  workmanlike  man- 
ner and  both  material  and  workmanship  shall  be  subject  to  the 


*  Insert  here  the  class  of  inspection  desired,   that  is,   Standard,  Merchantable, 
or  Prime.     See  "Specifications  for  Classification  and  Inspection  of  Lumber". 


271 


52  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

inspection  and  approval  of,  or  rejection  by,  the  Engineer.  Only 
the  timber  actually  called  for  in  the  plans  shall  be  estimated  and 
paid  for.  No  allowance  shall  be  made  for  waste. 

INTERSTATE   RULES   OF   1905   FOR  THE   CLASSIFICATION   AND 
INSPECTION  OF  YELLOW  PINE  LUMBER 

EFFECTIVE  OX  AXD  AFTER  FEBRUARY  1,  1905 

General  Rules 

All  the  lumber  must  be  sound  commercial  long-leaf  yellow  pine  (pine  com- 
bining large  coarse  knots  with  coarse  grain  is  excluded  under  these  rules), 
well  manufactured,  full  to  size,  saw-butted,  and  free  from  the  following  defects: 
Unsound,  loose,  and  hollow  knots,  wormholes  and  knotholes,  and  through  shakes 
or  round  shakes  that  show  on  the  surface.  It  shall  be  square-edged,  unless 
otherwise  specified. 

A  through  shake  is  hereby  defined  to  be  a  fissure  through,  or  fissures 
connected  from  side  to  side,  edge  to  edge,  or  side  to  edge. 

In  the  measurement  of  dressed  lumber,  the  width  and  thickness  of  the 
lumber  before  dressing  must  be  taken;  less  than  1  inch  thick  shall  be  meas- 
ured as  1  inch. 

The  measurement  of  wane  shall  always  apply  to  the  lumber  in  the 
rough. 

Where  the  terms  "one-half  heart"  and  "two-thirds  heart"  are  used,  they 
shall  be  construed  as  referring  to  the  area  of  the  face  on  which  measured. 

In  the  dressing  of  lumber,  when  not  otherwise  specified,  one-eighth  inch 
shall  be  taken  off  by  each  planer  cut. 

Classification 

Flooring.  Flooring  shall  embrace  4,  5,  and  6  quarter  inches  in  thick- 
ness by  3  to  6  inches  in  width,  excluding  1*  X  6.  For  example:  1  X  3,  4, 
5,  and  6;  1J  X  3,  4,  5,  and  6;  1*  X  3,  4,  and  5. 

Boards.     Boards  shall  embrace  all  thicknesses  under  1$  inches  by  over 

6  inches  wide.    For  example:    f,  1,  li,  and  If  inches  thick  by  over  6  inches 
wide. 

Plank.  Plank  shall  embrace  all  sizes  from  14.  to  under  6  inches  in 
thickness  by  6  inches  and  over  in  width.  For  example:  14,  2,  2J,  3,  34,  4, 
44.,  5,  5i,  5J  by  6  inches  and  over  in  width. 

Scantling.  Scantling  shall  embrace  all  sizes  exceeding  14.  inches  and 
under  6  inches  in  thickness,  and  from  2  to  under  6  inches  in  width.  For 
example:  2  X  2,  2  X  3,  2  X  4,  2  X  5,  3  X  3,  3  X  4,  3  X  5,  4  X  4,  4  X  5,  and 
5X5  inches. 

Dimension.  Dimension  sizes  shall  embrace  all  sizes  6  inches  and  up  in 
thickness  by  6  inches  and  up  in  width.  For  example:  6  X  6,  6  X  7,  7  X  7, 

7  X  8,  8  X  9,  and  up. 

Stepping.  Stepping  shall  embrace  1  to  2J  inches  in  thickness  by  7 
inches  and  up  in  width.  For  example:  1,  li,  14,  2,  and  24  X  7,  and  up  in 
width. 


272 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  53 

Rough  Edge  or  Flitch.  Rough  edge  or  flitch  shall  embrace  all  sizes  1 
inch  and  up  in  thickness  by  8  inches  and  up  in  width,  sawed  on  2  sides  only. 
For  example:  1,  14,  2,  3,  4,  and  up  thick  by  8  inches  and  up  wide,  sawed  on 
2  sides  only. 

Inspection 

Standard.  All  lumber  shall  be  sound.  Sap  is  no  objection  and  wane 
.  may  be  allowed  one-eighth  of  the  width  of  the  piece  measured  across  the  face  of 
the  wane,  extending  one-fourth  of  the  length  on  one  corner,  or  its  equivalent  on 
two  or  more  corners,  provided  that  not  over  10  per  cent  of  the  pieces  of 
any  one  size  shall  show  such  wane. 

Merchantable.  All  sizes  under  9  inches  shall  show  some  heart  the 
entire  length  on  one  side;  sizes  9  inches  and  over  shall  show  some  heart 
the  entire  length  on  two  opposite  sides.  Wane  may  be  allowed  one-eighth  of  the 
width  of  the  piece  measured  across  the  face  of  the  wane,  and  extending 
one-fourth  of  the  length  of  the  piece  on  one  corner  or  its  equivalent  on  two  or 
more  corners,  provided  that  not  over  10  per  cent  of  the  pieces  of  any  one  size 
shall  show  such  wane. 

Prime.  Flooring.  Flooring  shall  show  one  heart  face,  free  from 
through  or  round  shakes  or  knots  exceeding  1  inch  in  diameter,  or  more 
than  4  in  a  board  on  the  face  side. 

Boards.  Boards  7  inches  and  under  in  width  shall  show  one  heart  face; 
over  7  inches  in  width,  they  shall  show  two-thirds  heart  on  both  sides,  all  free 
from  round  or  through  shakes,  large  or  unsound  knots. 

PlanJc.  Plank  7  inches  and  under  in  width  shall  show  one  heart  face; 
over  7  inches  in  width,  they  shall  show  two-thirds  heart  on  both  sides,  all  free 
from  round  or  through  shakes,  large  or  unsound  knots. 

Scantling.  Scantling  shall  show  three  corners  heart,  free  from  through  or 
round  shakes  or  unsound  knots. 

Dimension  Sizes.  All  square  lumber  shall  show  two-thirds  heart  on  two 
sides,  and  not  less  than  one-half  heart  on  two  other  sides.  Other  sizes  shall 
show  two-thirds  heart  on  face  and  show  heart  two-thirds  of  length  on  edges, 
excepting  when  the  width  exceeds  the  thickness  by  3  inches  or  over;  then  it 
shall  show  heart  on  the  edge  for  one-half  the  length. 

Stepping.  Stepping  shall  show  3  corners  heart,  free  from  shakes  and  all 
knots  exceeding  one-half  inch  in  diameter  and  not  more  than  6  in  a  board. 

Sough  Edge  or  Flitch.  Eough  edge  or  flitch  shall  be  sawed  from  good 
heart  timber  and  shall  be  measured  in  the  middle,  on  the  narrow  face,  free 
from  injurious  shakes  or  unsound  knots. 

Wane  shall  be  allowed  on  not  over  5  per  cent  of  the  pieces  in  any  one 
size,  as  on  merchantable  quality. 

TERRA  COTTA  DRAIN  PIPE  FOR  CULVERTS 

The  Contractor  shall  furnish  and  lay  vitrified  terra  cotta 
pipe,  according  to  place,  size,  and  length,  as  shown  on  the  plans 
and  profiles,  or  as  ordered  by  the  Engineer. 

Quality.  The  terra  cotta  pipe  shall  be  of  standard  lengths 
and  quality,  double  strength,  made  of  the  best  material,  thor- 


273 


54  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

oughly  and  perfectly  burned,  of  homogeneous  texture,  without 
imperfections,  and  well  glazed,  so  that  its  surfaces  shall  be 
smooth,  hard,  and  even.  The  pipe  shall  be  straight,  not  varying 
more  than  one-eighth  inch  from  a  straight  line  per  foot  of  length; 
true  to  form;  of  full  diameter  throughout;  of  a  thickness  at  least 
equal  to  that  of  double  strength  standard  sewer  pipe  and  of  the 
same  diameter ;  and  it  may  have  either  socket  or  sleeve  joints.  The 
bells  shall  be  of  standard  depth,  and  large  enough  to  receive  to 
their  full  depth  all  spigot  ends  without  clipping  and  to  leave  a 
space  of  not  less  than  J  of  an  inch  all  around  for  cement. 

Laying.  All  pipe  shall  be  laid  true  to  line  and  grade  given 
by  the  Engineer,  and  on  good  bottom.  Unless  timber  and  con- 
crete foundations  are  indicated  on  the  profile,  an  excavation  of 
at  least  6  inches  in  depth  to  receive  the  pipe  shall  be  made  to 
conform  to  the  shape  of  the  pipe.  The  pipe  shall  be  laid  in  such 
length  as  to  extend  at  least  1  foot  beyond  the  foot  of  the  slopes 
of  the  finished  embankment  unless  otherwise  ordered  by  the 
Engineer. 

Joints.  The  space  between  the  pipe  and  the  socket  shall  be 
as  uniform  as  possible,  and  shall  be  made  water-tight  by  first 
using  a  small  jute  gasket,  thoroughly  saturated  with  neat  cement, 
carefully  coiled  and  calked  in  the  bell  of  the  pipe.  The  joints 
shall  then  be  thoroughly  filled  with  cement  mortar,  made  of  equal 
parts  of  cement  and  clean  sharp  sand,  thoroughly  mixed  dry, 
water  enough  being  afterwards  added  to  give  it  the  proper  con- 
sistency, and  the  mortar  shall  be  used  as  soon  as  made ;  after  this 
the  joint  shall  be  carefully  wiped  inside  and  out,  and  pointed. 

Interior  of  Pipe.  The  interior  of  the  pipe  shall  be  carefully 
cleaned  of  all  dirt,  cement,  or  superfluous  materials  of  every 
description. 

The  Contractor  shall  make  good  all  defects  and  remove  any 
foreign  matter  which  may  have  been  left  in  or  otherwise  intro- 
duced into  the  pipe,  before  the  final  acceptance  of  the  work. 

Payment.  Drain  pipe  shall  be  estimated  and  paid  for  by  the 
linear  foot  in  place,  the  price  to  include  the  pipe,  the  hauling,  and 
placing  as  specified.  "Where  shown  on  the  profile,  end  walls  for 
the  drain  pipe  shall  be  constructed  of  masonry  in  accordance  with 
the  standard  plans  for  end  walls  for  pipe  culverts,  the  concrete 
for  same  to  be  paid  for  at  the  price  given  in  the  proposal  for  No.  2 
concrete. 

CAST=IRON  PIPE  CULVERTS 

The  Contractor  shall  furnish  and  lay  cast-iron  water  pipe 
according  to  place,  size,  and  length  as  shown  on  the  plans  and 
profiles. 


274 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  55 

Quality.  All  cast-iron  pipe  shall  be  free  from  such  defects 
and  imperfections  as  shall,  in  the  opinion  of  the  Engineer,  make 
it  unacceptable  for  use  as  pipe  culverts,  and  it  shall  be  of  standard 
thickness  and  length.  "Where  it  is  necessary  to  use  cut  pipe,  the 
cutting  shall  be  done  in  such  a  manner  as  to  leave  a  smooth  end 
at  right  angles  to  the  axis  of  the  pipe. 

Laying.  All  pipe  shall  be  laid  true  to  line  and  grade,  and  in 
such  lengths  that  the  ends  of  the  pipe  shall  extend  not  less  than 
1  foot  beyond  the  foot  of  the  slopes  of  the  finished  embankments, 
unless  otherwise  ordered  by  the  Engineer. 

Blocking.  Each  length  of  pipe  shall  be  laid  upon  blocking 
set  at  3  different  places  along  its  length.  It  shall  be  of  sound 
3-  by  10-inch  planking  and  shall  have  a  length  equal  at  least 
to  the  diameter  of  the  pipe.  Wedges  shall  be  placed  on  the 
blocking  to  hold  the  pipe  in  position.  The  blocks  shall  be  bedded 
firmly  and  evenly  across  the  line  of  pipe  and,  when  any  block 
has  been  sunk  too  deep,  additional  blocking  shall  be  placed  to 
bring  the  pipe  to  the  required  grade. 

Joints.  The  space  between  the  pipe  and  the  socket  or  collar 
shall  be  as  uniform  as  possible,  and  shall  be  made  water-tight  by 
being  thoroughly  filled  with  Portland  cement  mortar,  made  of 
equal  parts  of  an  approved  cement  and  clean  sharp  sand. 

Interior  of  Pipe.  The  interior  of  the  pipe  shall  be  carefully 
cleaned  of  all  dirt,  mortar,  or  superfluous  materials  of  every 
description.  The  Contractor  shall  make  good  all  defects  and 
remove  any  foreign  matter  which  may  have  been  left  in  or  other- 
wise introduced  into  the  pipe,  before  the  final  acceptance  of  the 
work. 

Payment.  Cast-iron  pipe  shall  be  estimated  and  paid  for  by 
the  linear  foot  in  place,  the  price  to  include  the  pipe,  the  hauling, 
and  the  placing  as  specified.  Where  shown  on  the  profile,  end 
walls  for  the  pipe  shall  be  constructed  of  masonry  in  accordance 
with  the  standard  plans  for  end  walls  for  pipe  culverts. 

STRUCTURAL  STEEL  FOR  BUILDINGS* 

Steel.  All  steel  may  be  made  by  either  the  Bessemer  or  the 
open-hearth  process,  except  rivet  steel  and  steel  for  plates  or 
angles  over  f  inch  in  thickness  which  are  to  be  punched,  and 
these  will  be  made  by  the  open-hearth  process.  The  finished 
products  shall  be  straight  and  free  from  flaws  and  shall  have 
clean  smooth  surfaces. 


See  specification  for  steel  under  Bridges,  p.  65,  as  another  example. 


275 


56  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Schedule  of  Requirements.     The  requirements  are  as  follows: 


CHEMICAL  AND  PHYSICAL  PROPERTIES 

STRUCTURAL 

RIVET 

Phosphorous  maximum    Bessemer 

0.10  per  cent 

Phosphorous  maximum,  open-hearth  

0.06  per  cent 

0.06    percent 
0  045  per  cent 

Tensile  strength,  Ibs.  per  sq    in  

55,000-65,000 

Desired 
48,000-58,000 

Elastic  limit,  minimum  per  sq.  in  

*  tens.  str. 
f  1,400,000 

$  tens.  str. 
f  1,400,000 

Elongation  in  2  in.  minimum  per  cent  
Character  of  fractiire.  .  . 

'|  tens.  str. 
22 
silkv 

1  tens.  str. 
silkv 

Bend  Tests.  The  test  specimens  for  plates,  shapes,  and  bars 
shall  bend  cold  through  180  degrees  without  cracking  on  the 
outside  of  the  bent  portion,  as  follows :  For  material  f  inch  to  and 
including  1^  inches  in  thickness,  around  a  pin  the  diameter  of 
which  is  equal  to  the  thickness  of  the  specimen ;  and  for  material 
over  1^  inches  in  thickness,  around  a  pin  the  diameter  of  which 
is  equal  to  twice  the  thickness  of  the  specimen.  For  pins 
and  rollers  the  test  specimen  shall  bend  cold  through  180 
degrees  around  a  1-inch  pin,  without  cracking  on  the  outside  of 
the  bent  portion.  For  rivet  steel  the  test  specimen  shall  bend 
cold  through  180  degrees,  flat  on  itself,  without  cracking  on  the 
outside  of  the  bent  portion. 

Annealing  Tests.  Material  which  is  to  be  used  without  anneal- 
ing or  further  treatment  shall  be  tested  in  the  condition  in  which 
it  comes  from  the  rolls.  When  material  is  to  be  annealed  or  other- 
wise treated  before  use,  the  specimen  representing  such  material 
shall  be  similarly  treated  before  testing. 

Test  Pieces.  For  each  melt  there  shall  be  furnished  by  the 
Contractor,  properly  prepared,  free  of  charge  to  the  railway 
company,  at  least  1  tensile  and  1  bending  test. 

Stock  Material.  No  material  shall  be  taken  from  stock  with- 
out the  consent  of  the  Inspector.  Such  material  shall  be  stamped 
with  the  original  melt  number  and  shall  not  have  more  than 
surface  rust.  In  any  case  in  which  the  rust  has  eaten  into  the 
material,  the  piece  shall  not  be  accepted. 

Shop  Work.  All  workmanship  shall  be  first  class  in  every  par- 
ticular and  all  parts  shall  be  neatly  finished. 

STEEL  BRIDGE  SPECIFICATIONS 

When  specifications  are  contained  in  letter  of  invitation,  or 
shown  on  accompanying  plan,  they  shall  supersede  those  herein 
which  conflict  therewith. 


276 


CIVIL  SPECIFICATIONS  AND  CONTRACTS 


57 


Should  any  question  arise  as  to  the  interpretation  of  these 

specifications,  the  decision  of  the  Chief  Engineer  of  the 

Company  shall  determine  the  matter. 

RAILROAD  BRIDGES 
General  Clauses 

Material.  All  bridges  shall  be  constructed  of  rolled  steel ;  but 
cast  iron  or  cast  steel  may  be  used  in  the  machinery  of  draw- 
bridges, and  wrought  iron  for  laterals  and  unimportant  members. 


Fig.  1.     Live  Load  Diagram  for  Railway  Bridges. 

Live  Load.  All  structures  shall  be  designed  to  carry,  in  addi- 
tion to  their  own  weight,  the  moving  load  shown  in  Fig.  1  or 
Fig.  2,  moving  simultaneously 

on    each    truck    in    the    same  3  *  «  s 

direction.  §  §  §  § 

For    transverse    trough    or  *  * 

buckled  plate  floors,  the  live 
load  shall  be  taken  at  16,000 
pounds  per  foot  of  track. 

Dead  Load.  The  dead  load 
shall  consist  of  the  weight  of 
the  metal  in  the  structure  and 
an  assumed  weight  of  500 


Fig. 


Live  Load  Diagram  for  Railway 
Bridges. 


pounds  per  lineal  foot  of  single  track  for  the  ordinary  wooden 
floor,  the  rails,  etc.  For  ballast  floors  the  following  weights 
shall  be  assumed : 

Ballast   120  Ibs.  per  cubic  foot 

Concrete    140  Ibs.  per  cubic  foot 

Asphalt    90  lbs-  Per  cubic  foot 

Lumber    54  Ibs.  per  cubic  foot 

Wind  Pressure.  For  girder  bridges  the  wind  pressure  against 
each  chord  of  the  bridge  shall  be  taken  at  200  pounds  per  lineal 
foot.  In  addition  to  this,  on  the  chord  which  carries  the  track,  a 


277 


58  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

wind  pressure  of  400  pounds  per  lineal  foot,  with  its  point  of 
application  7^  feet  above  the  rail,  shall  be  taken  as  a  moving 
load. 

For  viaducts  and  trestle  towers,  on  the  unloaded  structure, 
the  wind  pressure  shall  be  taken  at  50  pounds  per  square  foot  of 
the  projected  surface  of  two  trusses  and  two  sides  of  towers  on 
the  vertical  plane  through  the  axis  of  the  structure ;  on  the  loaded 
structure,  the  pressure  shall  be  taken  at  30  pounds  per  square 
foot  of  this  same  surface  and,  in  addition,  the  moving  wind  load 
specified  for  girder  bridges. 

For  determining  the  requisite  anchorage  for  the  loaded  struc- 
ture, the  train  shall  be  assumed  to  weigh  600  pounds  per  foot. 

Momentum  of  Train.  The  horizontal  force  developed  by  sud- 
denly stopping  a  train  shall  be  taken  at  one-fifth  of  the  moving 
load. 

Centrifugal  Force.  The  centrifugal  force  shall  be  taken  at 
2  per  cent  of  the  moving  load  for  each  degree  of  curvature  of  the 
track — all  the  tracks  being  loaded.  Centrifugal  force  shall  be 
considered  live  load. 

Spans.  The  spans  assumed  for  calculation  shall  be  as  fol- 
lows :  For  pin  bridges,  the  distance  between  centers  of  end  pins ; 
for  riveted  bridges,  the  distance  between  centers  of  end  bearings ; 
for  floor  beams,  the  distance  between  centers  of  trusses;  for 
stringers,  the  distance  between  centers  of  floor  beams. 

Depth.  The  depths  assumed  for  calculation  shall  be  as  fol- 
lows :  For  pin  bridges,  the  distance  between  centers  of  chord 
pins ;  for  riveted  bridges,  the  distance  between  centers  of  gravity 
of  flanges. 

Stress  Sheets  and  Plans.  All  parts  shall  be  so  designed  that 
the  stresses  coming  upon  them  can  be  accurately  calculated. 

Bidders  shall  submit  with  their  bids  a  general  plan  and  com- 
plete stress  sheet,  showing  the  loads  used  and  the  separate  stress 
produced  on  each  member  by  each  of  the  foregoing  loads  and 
forces,  and  the  sizes  and  arrangement  of  parts  in  sufficient  detail 
for  comparison  with  other  plans. 

Upon  award  of  contract  the  Contractor  shall  furnish  in  dupli- 
cate to  the  Chief  Engineer  of  the  railway  company  blueprints 
of  complete  shop  and  erection  plans  showing  all  details,  which 
shall  be  subject  to  the  approval  of  the  said  Chief  Engineer.  Upon 
completion  of  the  work  all  tracings  shall  be  delivered  to  the  Chief 
Engineer  of  the  railway  company.  Tracings  shall  be  of  uniform 
size,  and  not  larger  than  30  inches  by  42  inches. 

Clearance.  The  gage  of  the  track  is  4  feet  8J  inches,  and  the 
distance  between  the  tracks,  center  to  center,  is  13  feet. 


278 


CIVIL  SPECIFICATIONS  AND  CONTRACTS          59 

The  vertical  clearance  for  through  bridges  shall  be  22  feet 
above  the  top  of  the  rails. 

For  single-track  through  bridges,  on  tangent  with  rails  at  the 
same  level,  the  lateral  clear  width  at  the  top 
of  rails  shall  not  be  less  than  10  feet  6  inches ; 
from  a  height  of  2  feet  to  a  height  of  17-| 
feet,  it  shall  not  be  less  than  14  feet;  and 
at  a  height  of  22  feet,  it  shall  not  be  less  than 
6  feet  (see  Fig.  3). 

For  double-track  bridges  and  for 
curves  and  elevation  of  outside  rail,  the  lat- 
eral clear  widths  shall  be  increased  accord- 
ingly. 

Wood  Floor.  The  wood  floor  shall  be 
shown  as  a  standard  bridge  floor,  plan  tion^of  cieaTan^Dimen- 

dated  sions    on    Bridges. 

The  wood  floor  shall  be  continued  over  all  piers  and  back 
walls. 

Unit  Stresses  and  Sections 

To  provide  for  impact  and  vibrations  the  stresses  produced  by 
the  live  load  shall  be  increased  by  the  formula 

1=8      3°° 


s^M 


L-f  300 

where  /= amount  to  be  added  to  the  live  load  stress 
$  =  calculated  live  load  stress 

L  =  length  in  feet  of  the  loading  which  produces  the  maxi- 
mum stress  in  the  member 

The  unit  stresses  produced  by  the  foregoing  loads  and  forces, 
including  impact,  shall  not  exceed  the  following  values: 

tension,  net  section,    15,000  pounds  per  square  inch 
15,000  pounds  per  square  inch 


compression, 


1+    p 


13,500r2 

where  1  =  length  of  member,  center  to  center  of  connections,  in 

inches 
r  =  least  radius  of  gyration  in  inches 

No  compression  member  shall  have  a  length  exceeding  100 
times  its  least  radius  of  gyration,  except  that  wind  bracing  may 
have  a  length  equal  to  120  times  its  least  radius  of  gyration. 


279 


60  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Alternate  Stress.  Members  subject  to  alternate  tension  and 
compression  shall  have  a  net  sectional  area  equal  to  the  sum  of  the 
areas  required  for  the  separate  stresses. 

Counters.  "When  in  any  panel  the  shear  from  the  live  load, 
including  impact,  exceeds  seven-tenths  of  the  opposite  shear  from 
the  dead  load,  the  oblique  equivalent  of  this  excess  shall  be  provided 
for.  No  counter  rod,  however,  shall  have  a  smaller  section  than  1 
square  inch. 

Transverse  Loading.  In  deck  truss  bridges,  when  the  cross- 
ties  rest  on  the  chord,  the  sum  of  the  direct  thrust  per  square 
inch  and  three-fourths  of  the  fiber  stress  per  square  inch  pro- 
duced by  the  maximum  load  on  the  chord  panel  considered  as  a 
supported  beam — the  pins  being  in  the  neutral  axis  of  the  section 
— shall  not  exceed  the  allowable  compressive  stress,  the  proper 
amount  of  impact  being  added  to  each  kind  of  loading. 

Should  the  pins  be  out  of  the  neutral  axis,  the  additional  stress 
thus  produced  shall  be  provided  for. 

The  sum  of  the  direct  stress  per  square  inch  on  any  member, 
and  the  fiber  stress  per  square  inch  produced  by  its  own  wreight, 
shall  not  exceed  the  allowed  direct  stress  per  square  inch  by  more 
than  10  per  cent. 

Shop  Rivets  and  Pins.  The  shearing  stress  shall  not  exceed 
11,000  pounds  per  square  inch  of  section;  the  pressure  on  the 
bearing  surface  (diameter  X  thickness  of  bearing)  shall  not 
exceed  22,000  pounds  per  square  inch ;  the  fiber  stress  due  to 
bending,  considering  the  centers  of  the  bearings  at  the  points  of 
application  of  the  stresses,  shall  not  exceed  22,000  pounds  per 
square  inch. 

For  field-driven  rivets  a  deduction  of  20  per  cent  from  the 
above  values  shall  be  made. 

The  size  of  the  rivets  before  driving  shall  be  considered  their 
effective  size  for  calculation. 

Plate  Girders.  The  bending  moment  shall  be  considered  as 
resisted  solely  by  the  flanges,  with  no  portion  of  the  web  as- 
sisting. 

The  shear  in  webs  of  plate  girders  shall  not  exceed  10,000 
pounds  per  square  inch.  But  no  web  shall  be  less  than  three- 
eighths  of  an  inch  thick.  The  entire  end  shear  shall  be  considered 
as  transferred  into  the  flange  angles  in  a  distance  equal  to  the 
depth  of  web.  The  pitch  of  rivets  connecting  the  web  to  a  top 
flange  supporting  the  track  shall  not  exceed  3  inches. 

When  the  thickness  of  web  plate  is  less  than  one-thirtieth  of 
the  unsupported  distance  between  flange  angles,  stiffeners  shall  be 
riveted  on  both  sides  of  the  web,  with  fillers  as  thick  as  the  chord 


280 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  61 

angles,  and  with  close  bearings  against  both  flanges.  For  girders 
30  feet  long  and  less,  the  stiffeners  shall  be  3^  inches  by  3  inches 
by  §-inch  angles ;  for  girders  90  feet  long,  they  shall  be  5  inches  by 
3J  inches  by  f-inch  angles;  and  for  intermediate  lengths,  inter- 
mediate sized  angles. 

Generally,  the  stiffeners  shall  be  placed  at  intervals  equal  to 
the  depth  of  the  web,  with  a  maximum  limit  of  5  feet. 

Generally,  there  shall  be  two  pairs  of  stiffeners  over  each  bed 
plate,  their  combined  sectional  area  in  square  inches  being  equal 
to  the  total  end  shear  in  pounds,  including  impact,  divided 
by  15,000. 

Net  Section.  To  obtain  the  net  section  of  the  bottom  flange  of 
plate  girders  or  other  members,  all  the  rivet  holes  in  any  section, 
taken  £  inch  larger  in  diameter  than  the  rivet  to  be  used,  shall  be 
deducted. 

The  top  and  bottom  flanges  shall  have  the  same  gross  sec- 
tional area. 

Cover  plates  shall  be  at  least  12  inches  longer  than  the  net 
calculated  length.  When  over  14  inches  wide  there  shall  be  at 
least  4  lines  of  rivets,  with  pitch  not  exceeding  9  inches  in  any  of 
the  lines. 

Sway  Bracing.  Efficient  sway  bracing  and  lateral  bracing  on 
top  and  bottom  flanges  shall  be  provided.  Generally  this  bracing 
shall  be  of  the  same  sized  angles  as  the  intermediate  stiffeners. 
The  unsupported  length  of  flange  shall  not  exceed  12  times  its 
width,  except  as  noted  for  track  stringers. 

Track  Stringers  and  Floor  Beams.  Track  stringers  of  double 
track  through  bridges  and  deck  plate  girders  shall  generally  be 
spaced  6  feet,  center  to  center,  under  each  track.  For  single 
track  through  truss  bridges  the  stringers  shall  be  8  feet,  center 
to  center. 

Track  stringers  shall  be  riveted  into  the  floor  beams  and  shall 
bear  upon  the  bottom  flange  of  floor  beams,  or  upon  brackets 
which  bear  upon  the, bottom  flange  of  floor  beams;  but  the  value 
of  this  bearing  shall  not  be  considered  in  computing  the  number 
of  rivets  required  in  the  stringer  connections. 

Floor  beams  with  riveted  end  connections  shall  bear  on  the 
bottom  flange  of  the  main  girder,  or  on  a  bracket,  in  all  cases 
where  such  bearing  can  be  provided ;  but  the  value  of  this  bearing 
shall  not  be  considered  in  computing  the  number  of  rivets 
required  in  the  connection.  In  case  such  bearing  cannot  be  pro- 
vided, then  the  number  of  rivets  in  the  connection  shall  be  25  per 
cent  more  than  the  computed  number. 

In  the  connection  angles  between  the  stringers  and  floor 
beams,  and  other  similar  angles  or  plates,  the  shear  shall  not 


281 


62  CIVIL  SPECIFICATIONS  AND  CONTKACTS 

exceed  7000  pounds  per  square  inch;  but  no  connection  angle 
shall  be  less  than  five-eighths  of  an  inch  thick. 

When  the  length  of  stringer  exceeds  20  times  the  width  of 
flange,  lateral  bracing  shall  be  provided  between  the  flanges. 

The  webs  of  floor  beams  shall  be  of  the  same  thickness  at 
center  of  beams  as  at  the  ends. 

Minimum  Thickness.  The  minimum  thickness  of  metal  used 
shall  be  three-eighths  of  an  inch  except  for  lattice  bars  or  for 
fillers  where  a  lesser  thickness  is  required. 

Combined  Stresses.  In  case  the  sum  of  the  stresses  per  square 
inch  in  the  chords  and  end  posts  of  truss  bridges,  or  the  posts  of 
trestle  towers — due  to  the  live  load  including  impact,  the  dead 
load,  and  the  wind — shall  exceed  19,000  pounds  per  square  inch 
properly  reduced  for  compression,  the  section  shall  be  increased 
until  this  limit  is  not  exceeded. 

In  the  end  posts  of  through  bridges  the  sum  of  these  stresses 
added  to  the  maximum  fiber  bending  stress  per  square  inch,  pro- 
duced by  the  portal  bracing,  shall  not  exceed  20,000  pounds. 

Should  the  stresses  be  reversed  in  any  case,  proper  provision 
shall  be  made  for  such  stresses. 

Portals  and  Diagonal  Bracing.  All  through  spans  with  top 
lateral  bracing  shall  have  riveted  portal  bracing  composed  of 
angles,  latticed  as  deep  as  the  headroom  will  allow,  rigidly  con- 
nected to  the  end  posts. 

When  the  height  of  the  truss  exceeds  25  feet,  an  approved 
system  of  overhead  diagonal  bracing  shall  be  provided  at  each 
panel  point. 

Deck  bridges  shall  have  diagonal  bracing  at  each  panel  point 
proportioned  to  resist  the  unequal  loading  of  the  trusses;  the 
position  of  the  track,  and  the  action  of  the  wind  and  the  cen- 
trifugal force  being  considered. 

Pony  trusses  and  through  plate  girders  shall  be  stayed  by 
knee  braces  or  gussets  at  each  floor  beam  or  transverse  strut,  and 
at  the  ends. 

No  lateral  or  diagonal  rod  shall  have  a  smaller  area  than  1 
square  inch. 

Expansion  Rollers,  etc.  All  bridges  exceeding  75  feet  in 
length  shall  be  anchored  to  the  masonry  at  one  end,  and  shall 
have  at  the  other  end  nests  of  turned  Triction  rollers,  not  less 
than  4  inches  in  diameter,  running  between  planed  surfaces.  The 
pressure  per  lineal  inch  on  these  rollers  shall  not  exceed  1200\/d 
pounds — d  being  the  diameter  of  the  roller  in  inches. 

For  bridges  less  than  75  feet  in  length  one  end  shall  be  free 
to  move  on  planed  surfaces. 


282 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  63 

Variations  in  temperature  of  150°  F.  shall  be  provided  for. 

Provision  shall  be  made  at  movable  ends  against  side  motion. 

Bed  Plates.  The  pressure  of  bed  plates  on  the  masonry  shall 
not  exceed  400  pounds  per  square  inch.  When  two  spans  rest  on 
the  same  masonry,  a  continuous  rolled  plate  f  inch  thick  shall 
extend  under  the  adjacent  bearings. 

All  bed  plates  shall  have  efficient  stone  bolts  fastened  with 
sulphur  or  cement. 

Joints  and  Splices.  All  joints  in  riveted  work,  whether  in  ten- 
sion or  compression,  shall  be  fully  spliced. 

Chord  sections  shall  be  connected  at  abutting  ends  by  splices 
sufficient  to  hold  them  true  to  position,  and  to  transmit  the  shear- 
ing stress  at  the  joint. 

Web  plates  of  girders  shall  be  spliced  at  all  joints  by  a  plate 
on  each  side,  capable  of  transmitting  the  entire  shear  through 
the  splice  rivets. 

Rivets.  The  pitch  of  rivets  in  the  direction  of  the  stress  shall 
not  exceed  6  inches,  nor  sixteen  times  the  thickness  of  the  thinnest 
outside  plate  connected,  nor  be  less  than  three  times  the  diameter 
of  the  rivet.  At  right  angles  to  the  stress,  the  pitch  shall  not 
exceed  thirty  times  the  thickness  of  the  thinnest  outside  plate. 

At  the  ends  of  compression  members  the  pitch  shall  not  exceed 
four  diameters  of  the  rivet  for  a  length  equal  to  twice  the  width 
of  the  member. 

The  distance  from  the  edge  of  any  piece  to  the  center  of  rivet 
hole  generally  shall  be  not  less  than  1£  inches,  nor  more  than 
5  inches,  nor  more  than  8  times  the  thickness  of  the  plate. 

Tie  Plates.  All  segments  of  compression  members  connected 
by  latticing  only  shall  have  tie  plates  at  each  end,  the  rivets  and 
net  section  of  which  shall  be  sufficient  to  transfer  one-half  the  total 
maximum  stress  borne  by  the  segment,  and  the  thickness  of  which 
shall  be  not  less  than  one-fiftieth  of  the  distance  between  the  rivets 
connecting  them  to  the  compression  member.  In  no  case,  however, 
shall  the  length  of  the  tie  plate  be  less  than  its  width  across  the 
segments. 

Latticing.  The  open  sides  of  compression  members  shall  be 
stayed  by  tie  plates  at  the  ends,  and  by  intermediate  diagonal 
latticing. 

Generally,  the  thickness  of  single  lattice  bars  shall  not  be  less 
than  one-fiftieth,  and  the  thickness  of  double  bars,  connected  by  a 
rivet  at  their  intersection,  shall  not  be  less  than  one-sixtieth  of  the 
distance  between  rivets  connecting  them  to  a  member.  The  in- 
clination of  lattice  bars  with  long  axis  of  members  shall  approxi- 
mate 60  degrees  for  single  lattice  and  45  degrees  for  double  lattice, 


283 


64  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

and  the  distance  between  points  of  connection  of  the  latticing 
along  a  segment  shall  not  be  more  than  8  times  the  least  width  of 
the  segment.  The  width  of  lattice  shall  be  as  follows: 


LENGTH  OF  LATTICE 

WIDTH 

Under  10  inches 
Under  15  inches 
Under  20  inches 

2    inches 
2J  inches 
2^  inches 

For  the  chords  and  end  posts  of  truss  bridges  the  lattice  shall 
be  generally  3  inches  by  seven-sixteenth  inch. 

Pins.  The  members  bearing  against  any  pin  shall  be  so 
packed  as  to  produce  the  least  bending  moment  upon  the  pin, 
and  all  vacant  spaces  must  be  filled  with  filling  rings. 

All  pins  requiring  driving  shall  be  supplied  with  pilot  nuts 
for  use  in  erection. 

Preference.  Preference  will  be  given  to  details  which  will  be 
most  accessible  for  inspection  and  painting.  No  closed  sections 
will  be  allowed. 

Stiff  lateral  bracing  shall  be  preferred  for  use  between  the 
chords  which  carry  the  floor. 

Preferably  all  sections  shall  be  made  symmetrical,  and  the 
pins  placed  in  the  neutral  axis.  Bending  moments  at  connections 
shall  be  avoided  as  much  as  possible. 

Tension  at  the  foot  of  trestle  posts  shall  be  avoided  where 
practicable. 

Camber.  Truss  bridges  with  parallel  chords  shall  be  given  a 
camber  by  making  the  panel  lengths  of  the  top  chord  longer 
than  those  of  the  bottom  chord  in  the  proportion  of  one-eighth  of 
an  inch  to  every  10  feet. 

In  the  wood  floor  one-half  the  camber  shall  be  taken  out  unless 
otherwise  directed. 

Bolts.  "When  members  are  connected  by  bolts  which  transmit 
shearing  stress,  the  holes  shall  be  reamed  parallel  and  the  bolts 
turned  to  a  driving  fit. 

Screw  Ends.  In  tension  members  with  screw  ends,  the  area 
at  the  base  of  the  threads  must  be  at  least  15  per  cent  greater 
than  that  required  in  the  body  of  the  member. 

Upsetting,  etc.  The  heads  of  eyebars  and  the  enlarged  parts 
of  rods  with  screw  ends  shall  be  made  by  upsetting,  rolling,  or 
forging  into  shape.  Welds  in  steel  bars  will  not  be  allowed.  In 
iron  bars  they  will  only  be  allowed  to  form  the  loops  of  laterals, 
counters,  or  sway  rods. 


CIVIL  SPECIFICATIONS  AND  CONTRACTS 


65 


Quality   of   Material 

Steel.  All  steel  shall  be  made  by  the  open-hearth  process,  and 
shall  be  uniform  in  quality.  The  finished  products  shall  be 
straight,  free  from  flaws,  and  have  clean  smooth  surfaces. 

Identification  of  Material.  Copies  of  all  bills  of  material,  ship- 
ping lists,  and  complete  chemical  analyses  showing  the  amount  of 
phosphorus,  carbon,  sulphur,  and  manganese  shall  be  furnished 
by  the  Contractor  free  of  charge.  All  material  shall  be  plainly 
stamped  with  the  number  of  the  melt.  Rivet  and  lattice  steel 
and  other  small  parts  may  be  bundled,  with  the  above  marks  on 
an  attached  metal  tag. 

Schedule  of  Requirements.     The  requirements  are  as  follows: 


CHEMICAL  AND  PHYSICAL 
PROPERTIES 

STRUCTURAL 
STEEL 

RIVET  STEEL 

STEEL 
CASTINGS 

Phosphorous   maximum  ...  )  * 

.08 
.04 

.04 
.04 

.08 
.05 

Desired 

Desired 

Not  less  than 

Ultimate     Tensile     Strength     per 

60,000 

50,000 

65,000 

Elastic   Limit   not   less  than  

V2   Ten.  Str. 

3/2    Ten.    Str. 

.45  Ten.   Str. 

Elongation,    minimum    per    cent 

1,500,000 

1,500,000 



Ult.  Ten.  Str. 

Ult.    Ten.     Str. 

Elongation,  minimum  per  cent  in 

2  inches    

18 

Character  of  fracture  

Silky 

Silky 

[Silky  or  fine 
(granular 

Cold  Bends.  Samples  of  structural  and  rivet  steel  up  to 
seven-eighths  inch  in  thickness  shall  bend  to  close  contact  without 
fracture  on  the  convex  side.  For  greater  thickness,  sample  shall 
bend  180  degrees  to  a  curve  of  diameter  equal  to  thickness  of 
specimen,  without  fracture. 

Samples  of  cast  steel  1  inch  by  one-half  inch  shall  bend  90 
degrees  around  a  diameter  of  1  inch  without  fracture  on  outside. 

Tensile  Tests.  Tensile  tests  of  steel  showing  an  ultimate  tensile 
strength  within  5000  pounds  of  that  desired  will  be  considered 
satisfactory,  except  that  if  the  ultimate  strength  varies  more 
than  4000  pounds  from  that  desired,  a  retest  shall  be  made  on 
the  same  gage  which,  to  be  acceptable,  shall  be  within  5000  pounds 
of  the  desired  ultimate. 

Chemical  Analyses.  Check  chemical  analyses  shall  be  made 
from  the  finished  material,  if  called  for  by  the  Chief  Engineer,  in 
which  case  an  excess  of  25  per  cent  above  the  required  limits  will 
be  allowed. 

Material  which  is  to  be  used  without  annealing  or  further 


285 


66  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

treatment  shall  be  tested  in  the  condition  in  which  it  comes  from 
the  rolls.  When  material  is  to  be  annealed  or  otherwise  treated 
before  use,  the  specimen  representing  such  material  shall  be  simi- 
larly treated  before  testing. 

Drifting.  Material  punched  as  in  ordinary  practice,  shall 
stand  drifting  until  the  diameter  of  the  hole  is  increased  50  per 
cent  without  cracking  in  the  periphery  of  the  hole  or  in  the 
external  sheared  or  rolled  edge. 

Test  Pieces.  For  each  melt  there  shall  be  furnished  by  the 
Contractor,  properly  prepared,  free  of  charge  to  the  railway 
company,  at  least  one  tensile  and  one  bending  test.  Drifting 
tests  shall  be  furnished  occasionally  during  the  progress  of  the 
work. 

In  general,  tests  shall  be  selected  to  cover  extreme  gages. 
Material  will  not  be  accepted  on  tests  cut  from  pieces  of  radically 
different  size  or  section  from  that  used  in  the  work. 

Every  test  specimen  shall  be  at  least  one-half  square  inch  in 
area,  and  shall  be  planed,  sawed,  or  turned  with  sides  parallel.. 

Plates.  Plates  up  to  36  inches  wide  shall  be  rolled  in  a  universal 
mill.  Long  plates  shall  not  be  more  than  one-half  inch  out  of  line 
in  a  length  of  20  feet,  nor  three-fourths  inch  in  a  length  of  40  feet. 

Variation  in  Gage.  All  shapes  shall  be  rolled  to  gage.  All 
plates,  both  sheared  and  universal,  shall  be  of  specified  gage  on 
edges.  Shapes  or  plates  3  per  cent  less  than  thickness  specified 
shall  be  rejected,  except  that  in  the  case  of  plates  80  inches  wide 
or  over  a  variation  of  5  per  cent  will  be  allowed. 

Stock  Material.  No  material  shall  be  taken  from  stock  without 
the  consent  of  the  Inspector.  Such  material  must  be  stamped 
with  the  original  melt  number,  and  must  not  have  more  than  a 
surface  rust.  If  any  piece  of  material  sent  either  from  the  mill 
or  stockyard  is  rusted  when  needed  in  the  shop,  this  rust  must  be 
scraped  off  before  the  piece  is  punched.  In  any  case  in  which  the 
rust  has  eaten  into  the  material,  the  piece  will  not  be  accepted. 

Full-Sized  ~Eyebar  Tests.  Full-sized  tests  shall  be  ordered  by 
the  Engineer,  and  in  general  will  be  not  more  than  4  per  cent  of 
the  total  number  of  bars  in  the  structure. 

The  bars  shall  show  an  ultimate  strength  of  not  less  than 
55,000  pounds  per  square  inch;  an  elastic  limit  of  not  less  than 
one-half  the  ultimate  strength ;  and  an  elongation  taken  between 
the  necks  of  the  bars  of  not  less  than  12  per  cent,  for  bars  20  feet 
and  less  between  necks.  For  bars  exceeding  20  feet,  the  elonga- 
tion shall  be  not  less  than  10  per  cent. 

Fracture.  In  all  full-sized  tests,  75  per  cent  of  the  fractured 
area  shall  be  silky,  the  remainder  fine  granular. 

Retests.     If  one  bar  of  a  lot  breaks  in  the  head  but  fulfills  the 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  67 

above  requirements,  the  lot  shall  not  be  rejected  on  that  account. 
If  several  bars  break  in  the  head  but  fulfill  the  above  require- 
ments, an  additional  bar  for  a  retest  shall  be  furnished  by  the 
Contractor  free  of  cost  to  the  railway  company.  If  more  than 
one-third  of  the  total  number  of  bars  tested  break  in  the  head  the 
entire  lot  of  bars  shall  be  rejected. 

Full-sized  members  tested  to  destruction  shall  be  paid  for  by 
the  Company  at  cost,  less  their  scrap  value,  if  they  fulfill  the 
requirements  specified.  If  they  do  not,  they  shall  be  paid  for  by 
the  Contractor. 

Cast  Steel.  All  steel  castings  shall  be  practically  free  from 
blowholes  and  shall  be  thoroughly  annealed. 

Wrought  Iron.  All  wrought  iron  shall  be  tough,  ductile, 
fibrous,  and  of  uniform  quality.  Finished  bars  shall  be  perfectly 
welded  and  have  a  smooth  finish  throughout,  free  from  cinder 
spots,  blisters,  cracks,  buckles,  or  imperfect  edges. 

Test  specimens  shall  show  an  ultimate  strength  of  50,OQO 
pounds  per  square  inch,  an  elastic  limit  of  at  least  26,000  pounds 
per  square  inch,  an  elongation  of  at  least  20  per  cent  in  a  length 
of  8  inches,  and  shall  stand  bending  cold  180  degrees  to  a  curve 
of  diameter  equal  to  twice  the  thickness  of  specimen,  without 
sign  of  fracture. 

Cast  Iron.  Unless  otherwise  specified,  all  castings  shall  be 
tough  gray  iron,  free  from  cracks,  cinders,  blowholes,  or  other 
imperfections,  and  of  workmanlike  finish. 

Sample  pieces  1  inch  square,  cast  from  the  same  heat  of  metal 
in  sand  molds,  shall  be  capable  of  sustaining,  on  a  clear  span 
of  4  feet  6  inches,  a  central  load  of  500  pounds  when  tested  in 
the  rough  bar. 

Timber.  Unless  otherwise  specified,  the  timber  shall  be  first- 
class  Southern  long-leaf  yellow  pine,  sawed  true  and  out  of  wind ; 
full  size;  free  from  wind  shakes,  large  or  loose  knots,  or  other 
defects  impairing  its  strength  or  durability;  and  equal  in  quality 
to  grade  of  "Prime",  in  Interstate  Rules  of  1905  for  classification 
of  yellow  pine  lumber.  (See  page  52.) 

Shop  Work 

Workmanship.  All  workmanship  shall  be  first  class  in  every 
particular  and  all  parts  neatly  finished. 

Straightening.  All  material  shall  be  thoroughly  straightened 
in  the  shop,  before  being  laid  off,  by  methods  that  will  not  injure 
it  and,  if  bent  by  punching,  shall  be  again  straightened  before 
bolting  up. 

Punching.     In  all  punched  work  the  diameter  of  the  die  shall 


287 


68  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

be  not  more  than  one-sixteenth  inch  greater  than  the  diameter  of 
the  punch. 

All  holes  shall  be  perpendicular  to  the  surface  of  the  punched 
piece,  and  be  clean-cut,  without  torn  or  ragged  edges. 

Rivet  holes  shall  be  so  accurately  spaced  and  punched  that, 
when  the  parts  of  a  member  are  assembled,  a  rivet  one-sixteenth 
inch  less  in  diameter  than  the  hole  can  be  entered  hot  into  the 
holes.  Occasional  variations  shall  be  corrected  by  reaming. 

Reaming.  Steel  up  to  and  including  a  thickness  of  five- 
eighths  inch  may  be  punched  without  subsequent  reaming.  Steel 
of  greater  thickness  than  five-eighths  inch  shall  be  drilled  or 
punched  one-eighth  less  than  the  diameter  of  the  rivet  and  reamed 
to  a  diameter  of  one-sixteenth  inch  greater  than  the  diameter  of 
the  rivet.  The  reaming  of  the  rivet  holes  may  be  done  after  the 
various  pieces  have  been  punched  and  assembled,  but  every  hole 
after  reaming  shall  show  that  the  reamer  has  everywhere  touched 
the  metal.  Sheared  edges  and  ends  in  all  metal  over  five-eighths 
inch  in  thickness  shall  be  planed  at  least  one-eighth  inch. 

Riveting.  The  rivet  when  driven  shall  completely  fill  the 
holes,  have  full  round  heads  concentric  with  the  rivet,  of  a  height 
not  less  than  three-fifths  the  diameter  of  the  rivet  (unless  other- 
wise shown  on  the  plans),  and  in  full  contact  with  the  surface,  or 
be  countersunk  when  so  required. 

Rivets  shall  be  machine  driven  wherever  possible,  by  machines 
capable  of  retaining  the  applied  pressure  after  the  upsetting  is 
completed.  Pneumatic  hammers  shall  be  used  in  preference  to 
hand  driving. 

Tightening  rivets  by  calking  or  re-cupping  will  not  be  allowed. 

Finished  Members.  Built  members,  when  finished,  shall  be 
true  and  free  from  twist,  kinks,  buckles,  or  open  joints  between 
the  component  pieces. 

Eyebars.  Before  boring,  each  eyebar  shall  be  properly  an- 
nealed and  carefully  straightened.  They  shall  be  free  from 
flaws;  of  full  thickness  in  the  neck;  the  thickness  of  the  heads 
shall  not  be  more  than  one-sixteenth  inch  greater  than  the  thick- 
ness of  the  bar;  and  the  hole  shall  be  in  the  center  of  the  head 
and  on  the  center  line  of  the  bar.  No  forge  work  shall  be  done 
on  bars  after  they  are  bored. 

No  variation  from  the  calculated  length  between  pinholes  of 
more  than  one-sixty-fourth  of  an  inch  for  each  25  feet  will  be 
allowed.  Whenever  bars  are  to  be  packed  more  than  one-eighth 
of  an  inch  to  the  foot  of  their  length  out  of  parallel  with  the  axis 
of  the  structure,  they  shall  be -bent  with  a  gentle  curve  until  the 
head  stands  at  right  angles  to  the  pin  in  their  intended  position 
before  being  bored.  All  bars  belonging  to  the  same  panel  shall  be 


288 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  69 

placed  in  a  pile  and  shall  allow  the  pins  to  pass  through  both  ends 
at  the  same  time  without  forcing. 

Pins  and  Pinholes.  Pins  shall  be  turned  straight  and  smooth, 
and  shall  fit  the  pinholes  within  one-fiftieth  of  an  inch  for  pins  4 
inches  or  less  in  diameter,  and  within  one-thirty-second  of  an 
inch  for  larger  pins. 

Pinholes  shall  be  bored  clean  and  smooth,  to  a  true  parallel 
with  one  another,  within  one-thirty-second  of  an  inch  of  the 
specified  distance  apart,  center  to  center,  and  at  right  angles  to 
the  axis  of  the  member,  unless  otherwise  shown  on  drawings. 

Facings.  Eyes  of  laterals,  stirrups,  sway  rods,  and  counters 
shall  be  bored. 

All  abutting  surfaces  in  compression  members  shall  be  truly 
faced  to  even  bearings. 

The  ends  of  track  stringers  and  floor  beams  shall  be  faced 
true  and  square. 

Reaming.  All  holes  for  field  rivets  except  those  for  lateral 
and  sway  bracing  connections  shall  be  drilled  to  an  iron  template 
or  reamed  while  the  parts  are  temporarily  put  together. 

Shop  Erection.  Adjoining  chord  sections  shall  be  fitted  to- 
gether in  the  shop  and  all  parts  match  marked;  and  when  so 
fitted  their  abutting  ends  must  be  in  full  contact  and  the  two 
sections  in  perfect  alignment. 

Other  parts  of  the  structure  shall  be  erected  in  the  shop  when 
so  required  by  the  Inspector. 

Rivets.    In  riveted  steel  work  all  rivets  shall  be  of  steel. 

General  Annealing.  All  members  or  parts  of  members  which 
have  been  partly  heated  or  worked  at  blue  temperatures  shall 
be  properly  annealed. 

Painting 

Painting  in  Shop.  Before  leaving  the  shop  all  work  shall  be 
thoroughly  cleaned  from  all  loose  scale  and  rust,  and  given  one 
good  coat  of  pure  linseed  oil,  well  worked  into  joints  and  open 
spaces. 

In  rivet  work,  the  surface  to  come  in  contact  shall  be  painted 
before  riveting  together. 

Parts  which  are  not  accessible  for  painting  after  erection 
shall  have,  in  addition  to  the  coat  of  oil,  two  coats  of  paint 
before  erection. 

Painting  After  Erection.  After  erection,  the  entire  structure, 
except  the  wood  floor,  shall  be  thoroughly  and  evenly  painted 
with  two  coats  of  paint,  by  practical  painters.  The  two  coats 
shall  be  different  in  color. 


289 


70  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

When  work  is  delivered  f .  o.  b.,  ready  to  be  dropped  into  place, 
it  shall  be  given  only  the  above  coat  of  oil  before  loading. 

Materials.  The  materials  for  the  field  paint  will  be  furnished 
by  the  railway  company  to  the  Contractors  at  the  freight  station 
nearest  the  bridge  at  the  following  prices :  For  the  paste,  — 
( — )  cents  per  pound;  for  the  Japan,  —  dollar  and  —  cents  ($ — ) 
per  gallon,  and  for  the  linseed  oil,  —  ( — )  cents  per  gallon. 

No  material  shall  be  painted  or  oiled  when  it  is  wet. 

Pins,  pinholes,  screw  threads,  and  other  machine-finished 
bearing  surfaces  shall  be  coated  with  white  lead  and  tallow 
before  leaving  the  shop. 

Inspection 

Inspection  Facilities  Furnished  by  Contractor.  Due  notice 
that  material  is  ready  for  inspection  shall  always  be  given. 

All  facilities  for  inspection  of  material  and  workmanship 
shall  be  furnished  by  the  Contractor,  and  free  access  to  any 
works  in  which  any  portion  of  the  material  is  made  shall  be 
allowed. 

The  Contractor  shall  furnish,  free  of  cost,  the  use  of  an  effi- 
cient testing  machine  at  all  mills  where  any  of  the  material  may 
be  manufactured. 

Such  specimens  (prepared)  as  may  be  required  for  testing 
shall  be  promptly  furnished,  without  charge,  by  the  Contractor. 

No  shop  work  shall  be  done  on  any  material  until  it  has  been 
inspected  and  accepted. 

Copies  of  all  shipping  invoices  from  mills  or  shops  shall  be 
promptly  furnished  the  Inspector. 

No  material  shall  be  loaded  for  shipment  until  it  has  been 
accepted  by  the  Inspector. 

The  acceptance  by  an  Inspector  of  any  material  or  workman- 
ship shall  not  prevent  the  rejection  of  the  same,  if  it  is  afterwards 
discovered  to  be  defective. 

Erection 

Previous  to  and  during  erection  all  material  shall  be  kept 
clean,  and  shall  be  carefully  handled,  so  as  not  to  injure  any 
of  the  parts. 

Replacing  Bridge.  In  case  of  replacing  a  bridge,  the  Con- 
tractor shall  carefully  take  down  the  old  structure  and  neatly 
pile  the  material  at  some  point  near  the  bridge  convenient  for 
loading  on  cars.  If  the  old  bridge  is  to  be  erected  again,  special 
care  shall  be  taken  not  to  injure  any  of  the  parts,  and  the  differ- 
ent pieces  shall  be  plainly  marked  at  connections  by  the  Con- 
tractor, in  order  to  facilitate  re-erection.  All  material  in  the 
old  structure  shall  remain  the  property  of  the  railway  company. 


290 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  71 

Staging  and  False  Work.  The  Contractor  shall  furnish  all 
staging  and  false  work,  and  provide  for  carrying  traffic  during 
erection,  and  so  prosecute  his  work  as  to  interfere  as  little  as 
possible  with  the  traffic  over  the  bridge,  or  under  the  bridge,  if 
there  should  be  any  such. 

Any  work  affecting  the  safety  of  the  track  shall  be  sub- 
ject to  the  direction  of  the  Division  Superintendent  of  the 
Railway  Company. 

Main  Work.  The  Contractor  shall  furnish,  erect,  and  adjust 
the  entire  structure,  including  the  wooden  floor,  complete,  ready 
for  the  rails.  He  shall  also  remove  all  false  work  after  the 
erection  is  completed,  and  repair  any  damage  produced  by  his 
operations. 

Watchmen.  The  Contractor  shall  provide  watchmen  and 
other  safeguards  during  erection,  and  shall  be  responsible  for 
any  accident  or  damage  to  person  or  property  arising  from 
his  negligence  or  default;  and  he  shall  comply  with  all  laws, 
ordinances,  and  regulations  of  properly  constituted  authorities, 
should  there  be  any  such  affecting  the  work. 

The  Contractor  shall  be  responsible  for  the  work  until  it  is 
finally  completed  and  accepted  by  the  Chief  Engineer  of  the 

Railway  Company. 

HIGHWAY  BRIDGES 

Loads.  Highway  bridges  shall  be  proportioned  to  carry  the 
following  moving  loads  in  addition  to  their  own  weight: 

On  the  floor  system  for  all 

spans    100  pounds  per  square  foot  of  floors 

Or  a  concentrated  load  of 

8  tons  on  two  pairs  of 

wheels,    8   feet   centers 
On  the  trusses,  for  spans  of 

60  feet  or  less 100  pounds  per  square  foot  of  floors 

On  the  trusses,  for  spans  60 

feet  to  125  feet 80  pounds  per  square  foot  of  floors 

On   the  trusses,   for   spans 

over  125  feet 60  pounds  per  square  foot  of  floors 

Impact.  Allowance  for  impact  shall  be  one-half  as  great  as 
for  railroad  bridges. 

Unit  Stresses.  The  allowed  unit  stresses  shall  be  the  same  as 
for  railroad  bridges. 

On  yellow  pine  floor  joists  the  allowed  fiber  stress  shall  be 
1600  pounds  per  square  inch. 


201 


72  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Requirements.  The  requirements  as  to  quantity  of  material, 
workmanship,  painting,  erection,  etc.,  shall  be  the  same  as 
hereinbefore  specified  for  railroad  bridges. 

PRICE 

Bidders  shall  name  in  their  bids  a  lump  sum  for  furnishing 
and  transporting  all  labor  and  materials  of  every  kind  neces- 
sary to  complete  the  superstructure  in  place,  ready  for  the  rails 
in  railroad  bridges,  or  ready  for  the  traffic  in  highway  bridges, 
in  strict  accordance  with  these  specifications.  Bidders  shall  state 
in  their  tenders,  that  for  the  price  named  they  will  complete  the 
superstructure  at  or  before  a  specified  time ;  and  if  it  is  not  com- 
pleted at  the  specified  time,  the  price  shall  be dollars 

less  than  the  sum  named,  for  every  day  after  the  specified  time 
that  the  structure  remains  unfinished;  provided  that  no  reduc- 
tion in  price  shall  be  made  for  delay  caused  by  the  masonry  not 
being  ready  to  receive  the  superstructure. 

TUNNELS 

Approach  Cuts.  The  approach  cut  shall  be  excavated  to  such 
widths  and  slopes  as  the  said  Chief  Engineer  may  direct,  and 
all  the  materials  from  the  cuts  and  the  ends  of  the  tunnels  shall 
be  placed  in  embankments  on  the  line  of  the  railroad,  on  roads 
adjacent,  or  wasted,  as  the  said  Chief  Engineer  may  direct,  and 
they  shall  be  classified  and  paid  for  according  to  the  excavation 
classification  of  these  specifications. 

Dimensions.  Tunnels  shall  be  of  such  width  and  height  as 
the  said  Chief  Engineer  may  direct,  and  shall  be  excavated  in 
conformity  with  the  cross  section  to  be  furnished  by  him.  If 
the  tunnel  requires  support,  and  timber  is  adopted,  the  area  of 
its  cross  section  shall  be  enlarged  and  measured  3  inches  outside 
the  lagging;  or,  if  masonry  is  adopted,  6  inches  outside  the 
exterior  lines  of  the  side  walls  and  arching. 

Classification  and  Price  of  Excavations.  Materials  from 
tunnel  excavation  shall  be  paid  for  by  the  cubic  yard,  or  by  the 
lineal  foot,  completed,  in  case  such  bid  is  accepted.  The  price 
paid  shall  cover  all  materials  contained  between  the  two  portals', 
and  strictly  in  all  cases  within  the  lines  of  the  normal  or  enlarged 
cross  section  furnished  from  time  to  time  by  the  said  Chief  Engi- 
neer, and  shall  include  the  cost  of  all  temporary  supports,  such  as 
props,  scaffolding,  strutting,  etc.,  that  may  be  necessary  to  secure 
a  safe  prosecution  of  the  work  in  advance  of  the  introduction 
of  permanent  supports  of  timbering  or  masonry,  which  tempo- 


CIVIL  SPECIFICATIONS  AND  CONTKACTS  73 

rary  supports  shall  in  all  cases  be  removed  by  the  said  Contractor 
at  his  own  expense  after  or  concurrently  with  the  completion 
of  the  permanent  supports. 

Bottoms.  The  bottom  shall  be  picked  to  a  uniform  surface, 
and  no  rocky  protuberances  shall  be  allowed  inside  the  general 
line  of  the  sections. 

Drainage  Ditches.  The  drainage  ditch  through  the  center  of 
the  tunnel  shown  on  the  drawing  of  the  normal  cross  section 
shall  be  carefully  excavated  to  its  full  dimensions,  and  in  it 
shall  be  laid  broken  stone  in  such  manner  and  of  such  size  and 
form  as  the  said  Chief  Engineer  may  direct. 

Shafts.  The  said  Chief  Engineer  shall  determine  the  number 
and  location  of  shafts,  the  dimensions  of  which  shall  be  such  as 
he  may  direct.  The  excavation  price  paid  for  them  shall  be  by 
the  cubic  yard,  and  shall  cover  all  materials  contained  between 
the  surface  of  the  ground  and  soffit  of  the  tunnel,  and  within  the 
area  of  the  cross  section  furnished  by  the  said  Chief  Engineer. 
In  case  the  shaft  is  sunk  alongside  the  tunnel,  the  price  paid 
shall  cover  the  cost  of  such  curbing  or  other  supports  as  the 
sides  of  the  shaft  may  require ;  also  whatever  materials  or  labor 
may  be  required  for  ventilation  and  keeping  the  tunnel  and 
shafts  free  from  water;  and  shall  also  cover  all  hoisting  and 
pumping  machinery. 

Sumps.  The  excavation  of  all  necessary  wells  or  sumps  shall 
be  paid  for  at  the  same  price  per  cubic  yard  as  shaft  excavation. 

Niches.  Niches  or  openings  shall  be  left  in  the  walls  when 
and  at  such  points  as  the  Chief  Engineer  may  direct. 

Falls.  Drilling  and  blasting  shall  be  conducted  with  all  pos- 
sible care,  so  as  not  to  shatter  the  roof  and  the  sides  outside  the 
section  lines.  Any  falls  that,  in  the  judgment  of  the  said  Chief 
Engineer,  are  attributable  to  the  carelessness  or  want  of  proper 
skill  or  attention  on  the  part  of  said  Contractor,  shall  be  removed 
and  disposed  of  at  his  own  expense ;  but  if  by  unavoidable  acci- 
dent or  natural  causes  not  thus  attributable,  any  outside  rock 
shall  become  loose  or  shattered,  it  shall  be  removed  by  the  said 
Contractor,  and  a  just  and  equitable  allowance  shall  be  made 
by  the  said  Chief  Engineer  to  compensate  and  remunerate  him 
for  such  removal,  provided  a  claim  for  such  removal  be  made 
by  the  said  Contractor  during  the  month  in  which  a  fall  so 
occasioned  shall  occur. 

Permanent  Supports.  Should  it  be  determined  by  the  said 
Chief  Engineer  during  the  progress  of  the  work  that  any  tunnel 
or  any  portion  of  a  tunnel  requires  permanent  supports,  or  that 
the  shafts  require  lining,  timber  or  masonry  of  brick  or  stone 


*93 


74  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

may  be  used  for  such  supports  and  lining,  as  the  said  Chief 
Engineer  may  direct. 

Timber.  If  timber  is  used,  the  said  Chief  Engineer  shall  deter- 
mine its  description  and  quality  and  shall  prescribe  the  general 
plan  of  the  support,  and  it  shall  be  paid  for  by  the  1000  feet, 
board  measure,  framed,  and  placed  in  the  work. 

Iron  Work.  All  wrought-  and  cast-iron  work  ordered  by  the 
said  Chief  Engineer  and  used  in  the  work  shall  be  paid  for  by 
the  pound,  in  place. 

Masonry.  When  lining  or  arching  of  brick  or  stone  masonry 
shall  be  ordered,  it  shall  be  laid  in  the  most  skillful  and  workman- 
like manner,  and  strictly  in  accordance  with  the  plans  and  direc- 
tions prescribed  by  the  said  Chief  Engineer  from  time  to  time,  to 
suit  the  necessities  of  each  case  as  it  occurs. 

Should  it  be  determined  to  erect  masonry  facades  at  the 
portals  of  the  tunnels,  or  to  finish  out  above  the  surface  any  or 
all  of  the  shafts  with  ventilators,  such  work  shall  be  executed 
by  the  said  Contractor  in  accordance  with  such  plans  and  direc- 
tions as  may  be  prescribed  by  the  said  Chief  Engineer  for  the 
same. 

All  masonry  used  in  and  about  tunnels  shall  be  classified  and 
paid  for  under  the  masonry  classification  of  these  specifications. 

Timbering  Must  Follow  Excavation.  The  commencement, 
extent,  and  termination  of  all  permanent  timbering  and  masonry 
shall  be  determined  by  the  said  Chief  Engineer  and,  when  so 
determined,  such  timbering  or  masonry  must  progress  right  along 
with  the  excavation;  and,  if  necessary,  the  excavation  shall  be 
secured  and  protected  by  temporary  supports  before  the  intro- 
duction of  permanent  ones. 

Packing.  The  vacancies  behind  the  permanent  timber,  lag- 
ging, or  masonry  walls,  and  above  the  arching,  shall  be  filled 
with  concrete  and  dry  packing,  as  the  said  Chief  Engineer  may 
from  time  to  time  direct,  which  packing  shall  be  classified  and 
paid  for  under  the  masonry  classification  of  these  specifications. 
Dry  packing  shall  consist  of  hard  durable  stone,  approved  by 
the  said  Chief  Engineer,  broken  to  the  required  size  to  pack  well, 
and  shall  be  well  rammed  in. 

Work  Required  Before  Acceptance.  Before  tunnels  are 
accepted  their  whole  length  shall  be  entirely  cleared  of  debris, 
rubbish,  and  surplus  materials  of  every  kind,  and  the  bottom 
dressed  off  true  to  the  grade  line,  and  the  drains  cleaned  out, 
as  directed  by  the  Chief  Engineer. 

Night  Work  if  Required.  All  work  incident  to  the  construc- 
tion of  tunnels  shall  be  carried  on  by  2  shifts  of  10  hours  each, 
or  3  shifts  of  8  hours  each,  as  the  said  Chief  Engineer  shall  direct. 


294 


CIVIL  SPECIFICATIONS  AND  CONTRACTS          75 
BORINGS  FOR  A  SUBAQUEOUS  TUNNEL 

General  Specifications.  The  work  to  be  done  under  this 
contract  is  to  determine  carefully  by  borings  the  character  of 
materials  that  will  be  encountered  during  the  construction  of 

two  tunnels  under  the .River  and  under  streets 

of  both  the  Cities  of and.  .  The 

borings  shall  be  made  at  regular  intervals  100  feet  apart  on 
the  lines  as  shown  on  the  plan  attached  hereto. 

The  borings  on  land  will  approximate  3000  lineal  feet,  while 
those  taken  in  the  river,  measured  from  the  bottom  of  same,  will 
aggregate  about  2400  lineal  feet.  The  dotted  line  on  the  pro- 
files indicates  the  depth  to  w*hich  it  is  proposed  to  take  the 
borings.  No  payment  will  be  made  for  borings  made  to  a  greater 
depth  than  that  thus  indicated,  without  a  written  order  from  the 
Engineer. 

Quantities  Approximate.  It  will  of  course  be  understood  that 
the  approximate  quantities  given  above  are  not  to  be  used  in 
making  payment,  but  that  payments  will  be  made  upon  quan- 
tities determined  by  the  Engineer. 

Boreholes  Cased.  All  holes  bored  shall  be  cased  with  4-inch 
pipej  and  the  character  of  all  material  passed  through  from  the 
surface  of  the  ground  or  bottom  of  the  river  must  be  carefully 
determined,  and  the  depth  of  all  changes  in  the  stratification 
from  the  surface  of  the  ground  or  low  water  mark  shall  be  noted. 

Preservation  of  Samples.  Samples  of  the  various  materials 
encountered  shall  be  preserved  and  placed  in  glass  jars,  bottles, 
or  tubes,  as  the  Engineer  may  direct,  the  same  to  be1  carefully 
labeled,  giving  the  number  of  boring  and  the  depths  between 
wrhich  the  material  is  found.  Upon  the  completion  of  the  work 
all  samples  shall  be  delivered  at  the  office  of  the  Company. 

Borings  to  Rock.  If  directed  by  the  Engineer,  the  borings 
shall  be  carried  to  rock  formation  and  into  same,  to  hard  rock. 
Should  rock  be  encountered  above  the  dotted  line  shown  in  the 
drawing  (profile  drawing  should  always  be  submitted  with  regu- 
lar specifications),  borings  shall  be  carried  down  only  to  hard 
rock. 

Repaying.  Upon  the  completion  of  a  boring,  the  casing  pipe 
shall  be  withdrawn  and,  wherever  street  paving  shall  have  been 
disturbed  by  the  work,  it  shall  be  restored  to  its  original  condi- 
tion upon  the  completion  of  each  boring,  in  a  manner  satisfactory 
to  the  proper  city  officials,  without  cost  to  the  Company. 

Ground  Water.  A  record  shall  be  kept  at  each  borehole  on 
land,  of  the  depth  of  ground  water  below  the  surface  of  the 
ground. 


295 


76  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Price  to  Include.  Payment  will  be  made  for  all  borings  at 
the  price  per  vertical  foot  of  hole  bored,  no  allowance  being 
made  for  the  depth  of  the  water  where  the  boring  is  made; 
said  price  to  include  the  removal  of  all  material  excavated 
within  the  casing  and  all  pipe,  pumping  (with  the  proper  appli- 
ances and  appurtenances),  transportation,  glass  jars  or  tubes 
for  samples,  materials,  floats,  scows,  tools,  and  labor  necessary 
for  the  completion  of  the  above  described  work  in  the  best,  most 
rapid,  and  most  approved  manner. 

Violation  of  Laws.  The  Contractor  shall  assume  all  blame 
or  loss  by  reason  of  neglect  or  violation  of  the  United  States 
Government  or  municipal  laws,  regulations,  or  ordinances.  The 
Contractor  shall  place  sufficient  light  on  or  near  the  work,  keep 
the  light  burning  from  twilight  to  sunrise,  and  observe  such 
rules  relative  to  signals  and  safeguards  as  the  laws,  regulations, 
or  ordinances  require. 

Watchmen  and  River  Signals.  The  Contractor  shall  provide 
at  his  own  expense  the  necessary  watchmen,  signals,  and  lights, 
and  must  observe  the  local  laws  of  the  district  in  protecting  the 
public  against  all  injury  and  damage.  He  shall  conform  to  all 
the  rules  and  laws  relating  to  navigation  in  the  waters  crossed 
by  structures  covered  by  this  contract,  and  shall  notify  the 
proper  authorities  of  the  location  of  or  change  in  position  of 
proposed  structures  and  plant  in  said  waters,  and  shall  estab- 
lish and  maintain  the  necessary  lights,  fog  signals,  etc.,  upon 
structures  in  course  of  construction,  and  upon  his  plant.  In  case  of 
any  damage  resulting  from  neglect  to  keep  and  maintain  suit- 
able lights  and  signals,  or  from  mistake  in  signals,  it  must  be 
promptly  repaired  at  the  expense  of  the  Contractor. 

Inspection.  The  Contractor  shall  execute  the  work  under 
this  contract  in  the  presence  of  an  Inspector  at  all  times;  work 
done  in  absence  of  same  shall  be  subject  to  rejection. 


PILE  TRESTLE  FOR  AN  ELECTRIC  RAILROAD  ACROSS  AN 
OCEAN  INLET 

General  Specifications.  The  trestle  shall  consist  of  a  single 
track  structure  extending  out  from  either  shore  and  across  the 
various  channels,  as  shown  on  the  plans. 

The  piles  which  are  not  exposed  to  salt  water  shall  be  of 
white  oak,  while  the  other  piling  in  the  trestle,  fenders,  guard, 
and  rest  piers,  exposed  to  salt  water,  shall  be  treated  with  creo- 
sote oil  as  herein  specified,  the  timber  in  same  being  of  quality 
as  specified  under  "Piling". 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  77 

The  piles,  both  vertical  and  battered,  shall  be  jetted  and 
driven  to  the  depth  shown  on  the  plan.  They  shall  be  driven 
in  the  bents  of  the  trestle,  in  th?  guard  piers,  and  in  the  founda- 
tion for  piers,  for  the  watchmen'^  houses,  and  for  the  refuge  bays. 

The  quality  of  lumber  and  the  workmanship  on  all  structures 
shall  be  as  specified  under  "Timber  and  Framing".  Creosoted 
timber  and  galvanized  iron  shall  be  used  where  shown. 

The  trolley  poles  on  the  trestle  shall  be  of  Southern  long- 
leaf  yellow  pine,  35  feet  long,  sawed  to  octagonal  shape,  measur- 
ing not  less  than  8  inches  between  parallel  faces  at  the  top  and 
not  less  than  14  inches  between  faces  at  the  -base.  They  shall 
be  attached  to  the  trestle  as  shown,  securely,  and  in  a  workman- 
like manner,  and  shall  be  erected  accurately  to  line  and  grade. 

The  price  bid  for  the  work  shall  include  the  furnishing  and 
erection  of  all  lumber,  piles,  and  hardware  in  place,  complete 
with  all  appurtenances. 


TIMBER  AND  FRAMING 

Quality.  All  timber  must  be  sound,  straight  grained,  and 
free  from  excessive  sap,  loose  or  rotten  knots,  wind  shakes, 
wormholes,  or  any  other  defects  which  would  impair  its  strength 
or  durability.  It  must  be  sawed  or  hewn  perfectly  straight  to 
exact  dimensions,  with  full  corners  and  square  edges.  All  timber 
shall  be  long-leaf  yellow  pine  or  white  oak.  All  yellow  pine 
shall  be  long-leaf  Southern  yellow  pine,  and  must  satisfy  the 
requirements  under  "Merchantable  Inspection"  in  the  Interstate 
Rules  of  1905  for  the  classification  and  inspection  of  yellow  pine 
lumber. 

Workmanship.  Material  and  workmanship  shall  both  be 
subject  to  inspection,  and  approval  or  rejection,  by  the  Engineer. 
The  fenders,  rest,  and  guard  piers,  pile  trestle,  and  refuge  bays 
shall  be  built  according  to  the  plans  and  directions  given  by 
the  Engineer,  and  of  materials  as  specified  under  timber,  framing, 
and  iron  work. 

Framing.  All  framing  must  be  done  in  a  thorough  and 
workmanlike  manner.  No  open  joints,  blocking,  or  shims  will 
be  allowed;  the  bearing  of  caps  and  stringers  must  all  be  sized, 
and  perfect  bearings  must  be  secured  throughout.  The  side 
with  most  sap  shall  be  placed  downward.  All  timber  shall  be 
squared  off  with  the  saw.  The  holes  for  the  bolts  shall  be  bored 
with  an  auger  of  the  exact  diameter  of  the  bolts.  The  nuts  on 
all  bolts  shall  be  screwed  up  tight  so  that  the  washers  shall 
draw  hard  upon  the  timber  and  bring  all  parts  of  the  structure 
close  together. 


297 


78  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Surfacing  Ties.  All  bridge  ties  will  be  furnished  and  placed 
in  the  bridges  by  the  Contractor,  surfaced  and  brought  to  a  true 
plane  under  the  rails,  so  that  they  will  have  a  full  bearing  on 
the  four  stringers,  and  so  that  the  rails  will  have  an  even  bearing 
on  every  tie. 

Surfacing  Stringers.  All  track  stringers  shall  have  their 
upper  surfaces  brought  to  a  true  plane,  so  that  the  ties  may 
have  an  even  bearing  on  all  the  stringers. 

Elevating  Outer  Rail.  Where  any  framed  or  pile  trestle 
bridge  is  built  on  a  curve,  the  blocking,  or  other  means  for 
elevating  the  outer  rail,  will  be  as  per  detail  plans  furnished 
for  same.  When  mud  mills  are  used  for  supporting  either  framed 
trestle  bents  or  jack  stringers,  the  soil  shall  be  removed  and  a 
foundation  of  gravel  placed,  all  of  such  a  depth  and  rammed 
in  such  a  manner  as  the  Engineer  shall  direct,  without  cost  to 
the  Company. 

Inspection.  All  rejected  materials  must  be  removed  from 
the  Company's  premises  within  5  days  from  the  date  of  notice 
to  do  so. 

Payment.  The  price  bid  shall  include  the  framing  and  erec- 
tion of  all  the  timber  embodied  in  the  finished  structure  (exclu- 
sive of  the  piling,  which  shall  be  paid  for  as  specified  under 
"Piling").  The  price  shall  include  the  cost  of  hauling  from 
the  railroad  station,  or  wharf,  of  all  the  lumber,  spikes,  bolts, 
washers,  etc.,  furnishing,  framing,  and  erection;  all  to  be  done 
as  shown  on  the  plans  and  described  in  the  specifications. 

PILING 

Quality  and  Dimensions.  All  piles  shall  be  of  young,  straight, 
sound,  and  thrifty  white  oak,  yellow  pine,  or  other  timber  equally 
good  for  the  purposes,  acceptable  to  the  Engineer.  Piling  shall 
be  treated  with  creosoted  oil  where  shown  on  the  plans,  and  shall 
not  be  less  than  14  inches  in  diameter,  2  feet  from  the  butt. 

Piles  having  a  length  of  60  feet  and  over  shall  have  a  diameter 
at  the  point  of  not  less  than  7  inches. 

Piles  having  a  length  of  from  40  to  60  feet  shall  have  a 
diameter  at  the  point  of  not  less  than  7^  inches. 

Piles  having  a  length  of  from  30  to  40  feet  shall  have  a 
diameter  at  the  point  of  not  less  than  10  inches. 

Piles  of  less  length  than  30  feet  shall  have  a  diameter  at 
the.  point  of  not  less  than  10  inches,  exclusive  of  the  bark. 
When  sawed  off,  at  no  point  shall  they  be  of  greater  diameter 
than  18  inches.  They  shall  be  so  straight  that  a  line  stretched 


298 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  79 

from  the  center  of  the  pile  at  the  butt  to  the  center  of  the  pile 
at  the  tip  will  not  leave  the  center  of  the  pile  at  any  point  more 
than  2  inches  for  piles  20  feet  long,  4  inches  for  piles  30  feet 
long,  6  inches  for  piles  40  feet  long,  and  8  inches  for  piles  50 
feet  long.  No  short  or  sharp  bends  will  be  allowed.  All  knots 
shall  be  trimmed  close  to  the  body  of  the  pile,  and  the  bark 
peeled  before  placing  the  pile  in  the  leads  of  the  driver. 

Payments.  Piling  shall  be  paid  for  at  the  price  per  linear 
foot,  in  place,  given  in  the  proposal.  No  part  of  the  pile  shall 
be  paid  for  except  that  which  remains  in  the  work. 

Driving  Piles.  All  piles  shall  be  driven  to  a  depth  to  secure 
a  penetration  into  the  underlying  material  satisfactory  to  the 
Engineer.  It  is  probable  that  this  result  can  best  be  obtained 
by  the  use  of  a  water  jet  at  the  bottom  of  the  pile,  the  nozzle  of 
same  being  carried  below  the  point  of  the  pile.  After  piles  shall 
have  been  jetted  to  a  sufficient  depth  to  secure  the  required  stability, 
they  shall  be  driven  until  they  do  not  move  more  than  one-half  inch 
under  the  blow  of  a  hammer  weighing  2000  pounds,  falling  25 
feet  at  the  last  blow.  If  required,  5  additional  blows  from  the 
same  height  shall  then  be  delivered  and  the  pile  shall  then  be  con- 
sidered as  driven,  provided  the  one-half-inch  limit  be  not  exceeded 
under  any  of  the  last  5  blows.  They  must  be  driven  vertically, 
excepting  where  batter  piles  are  shown,  and  at  regular  distances 
apart  from  centers,  transversely  and  longitudinally,  as  required 
by  the  plans,  or  directions  of  the  Engineer;  they  must  be  cut 
off  squarely  at  the  butt,  and  be  well  sharpened  to  a  point  or 
cut  squarely  off,  as  the  Engineer  may  direct,  and  the  heads 
shall  be  bound  with  iron  hoops,  of  such  dimensions  as  he  may 
direct,  both  without  additional  cost  to  the  Company.  "Where  • 
batter  piles  are  required,  they  shall  be  driven  at  the  angle  shown 
on  the  plans.  All  piles  when  thus  driven  to  the  required  depth, 
shall  be  cut  off  square  and  horizontal  at  the  proper  height  given 
by  the  Engineer,  and  only  the  actual  number  of  linear  feet  of  the 
pile  left  for  use  in  the  structures,  after  being  driven  and  sawed  off, 
shall  be  paid  for.  No  splits  or  imperfect  piles  will  be  accepted. 
A  follower  of  approved  description  shall  be  used  when  directed 
by  the  Engineer.  Any  open  space  that  may  be  left  around  the 
driven  piles  shall  be  thoroughly  filled  with  beach  sand. 

After  creosoted  piles  have  been  driven  and  cut  off  to  the 
proper  height,  the  heads  shall  be  treated  to  an  application  of 
hot  creosote  oil  of  quality  as  herein  specified,  followed  by  a 
further  application  of  asphalt  thinned  with  oil. 

Price.  The  price  shall  include  the  hauling  of  the  piles  from 
the  point  of  delivery  to  the  point  where  they  are  to  be  driven, 
and  shall  be  per  linear  foot  of  piling  actually  left  in  the  work. 


80 


CIVIL  SPECIFICATIONS  AND  CONTRACTS 


Specifications   for   Standard   Piling  * 

Quality  of  Material.  Piling  shall  be  of  white,  post,  or  burr  oak, 
tamarack,  Norway  or  Southern  long-leaf  yellow  pine,  white  or  red  cedar,  red  or 
yellow  Douglas  fir,  or  red  or  swamp  cypress. 

All  piling  shall  be  cut  from  sound  live  trees  of  slow  growth,  firm  grain, 
and  free  from  ring  shakes,  decay,  large  unsound  knots,  or  other  defects 
that  will  impair  their  strength  or  durability.  They  shall  be  butt  cut  above 
the  ground  swell,  and  be  uniformly  tapering  from  the  butt  to  the  point. 
They  shall  be  so  straight  that  a  line  stretched  from  the  center  of  the  pile 
at  the  butt  to  the  center  of  the  pile  at  the  point,  will  not  leave  the  center 
of  the  pile  at  any  point  more  than  2  inches  for  piles  20  feet  long,  4  inches 
for  piles  30  feet  long,  6  inches  for  piles  40  feet  long,  and  8  inches  for  piles 
50  feet  long.  No  short  bends  will  be  allowed.  The  ends  shall  be  cut  square 
and  all  bark,  branches,  and  knots  shall  be  trimmed  off,  finishing  the  pile 
in  a  workmanlike  manner.  The  bark  must  be  peeled  before  placing  the  pile 
in  the  leads  of  the  pile  driver. 

Diameter  of  Piles.  The  diameter  of  piles  after  the  bark  is  peeled  from 
them,  shall  be  as  follows  for  the  different  kinds  of  timber: 


m 

<  * 

^ 

RED  OR 

&   %• 

2% 

2 

YEI..  DOUG. 

E^ 

£;£•* 

a^ 

$\ 

E9 

2 

e 

FIR. 

jjgS 

i 

II 

rr  -; 

II] 

§3 
feH 

P 

5 

UNDER 

OVER 
40* 

i-?-: 

Maximum  diameter  at  butt 

16* 

18* 

18* 

20* 

16' 

Minimum  diameter  at  butt 

14* 

14* 

14* 

12* 

14* 

16* 

14* 

Min.  diameter  6'  from  butt,      12* 

Min.  diameter  at  point  less 
than  30'  long  10* 

10* 

10* 

9* 

9* 

10* 

10* 

Min.     diameter     at     point 

from  31'  to  39'  long  i       9* 
Min.  diameter  at  point  40' 

10* 

9* 

8* 

8* 

10* 

9* 

and  over  in  length  
Per  cent  of  heart  

8* 

10* 
80 

9* 

8* 

8* 

75 

8* 
75 

8* 
100 

Driving  Piles.  All  piles  shall  be  driven  into  the  hard  bottom  until 
they  do  not  move  more  than  one-half  inch  under  the  blow  of  a  hammer  weighing 
2000  pounds,  falling  25  feet  at  the  last  blow,'or  a  hammer  and  fall  producing 
the  same  mechanical  effect. 

If  required,  five  additional  blows  from  the  same  height  shall  be  delivered, 
and  the  pile  shall  then  be  considered  as  driven,  provided  the  one-half  inch 
limit  be  not  exceeded  under  any  of  the  last  five  blows.  They  must  be 
driven  vertically  except  when  batter  piles  are  shown,  at  regular  distances 
apart  from  centers,  transversely  and  longitudinally,  as  required  by  the  plans 
or  directions  of  the  Engineer. 

They  must  be  cut  off  squarely  at  the  butt,  and  be  well  sharpened  to  a 
point  and,  when  necessary  in  the  opinion  of  the  Engineer,  shall  be  shod  with 
approved  wrought-iron  shoes  and  the  heads  bound  with  iron  hoops,  of  such 


*  Summary    of    Specifications    for    Piling    adopted    by    the    American    Railway 
Engineering  and  Maintenance  of  Way  Association. 


300 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  81 

dimensions  as  he  may  direct,  both  without  additional  cost  to  the  Company. 
When  batter  piles  are  required  they  shall  be  driven  at  the  angle  required 
on  the  plans,  and  shall  require  but  slight  bending  before  framing.  All 
piles  when  thus  driven  to  the  required  depths,  shall  be  cut  off  truly  square 
and  horizontal  at  the  proper  height,  and  shall  be  so  trimmed  as  to  leave 
no  horizontal  projection  outside  the  cap.  Only  the  actual  number  of  linear  feet 
of  the  pile  left  for  use  in  the  foundation  or  trestle,  after  being  driven  and 
sawed  off,  shall  be  paid  for.  No  split  or  imperfect  piles  will  be  accepted. 

TREATMENT  OF  TIMBER  WITH  CREOSOTE 

Quality,  Size,  etc.,  of  Timber.  Bridge  Timber.  All  bridge  tim- 
ber shall  be  of  'Georgia  or  Florida  long-leaf  yellow  pine  and 
must  be  inspected  under  the  Interstate  Rules  of  1905  for  the 
classification  and  inspection  of  yellow  pine  lumber,  to  meet  the 
requirements  of  either  Prime  Inspection  or  Merchantable  Inspec- 
tion, as  may  be  necessary  to  meet  the  conditions  and  which 
will  be  determined  in  advance  when  the  order  is  placed.  All 
bridge  timber  shall  be  treated  with  dead  oil  of  coal  tar,  and 
each  piece  after  treatment  must  contain  not  less  than  12  pounds 
of  oil  per  cubic  foot. 

Piles.  All  piles  shall  be  of  young,  straight,  sound,  and  thrifty 
Carolina  or  short-leaf  yellow  pine,  acceptable  to  the  Engineer, 
and  shall  be  treated  with  creosote  oil  as  herein  specified  as  to 

quality  and  method  of  treatment.  They  shall  be  not  less  than 

inches  in  diameter feet  from  butt,  and  shall  have  a  diameter 

at  the  point  of  not  less  than. ....inches,  exclusive  of  the  bark. 

Both  the  outside  and  inside  bark  shall  be  thoroughly  and  care- 
fully removed  before  the  piles  are  placed  in  the  cylinder  for 
treatment.  When  sawed  off,  at  no  point  shall  they  be  of  greater 
diameter  than  18  inches;  they  must  be  so  straight  that  the  pile 
at  no  point  deviates  by  more  than  one-half  of  its  diameter  from  a 
straight  line,  and  gradually  tapers  from  end  to  end.  The  ends 
must  be  cut  square  and  all  branches  and  knots  trimmed  off  to 
finish  the  pile  in  a  workmanlike  manner.  All  piles  shall  be  treated 
with  dead  oil  of  coal  tar,  and  each  pile  after  treatment  must 
contain  not  less  than  12  pounds  of  oil  per  cubic  foot. 

Crosstics.  All  crossties  shall  be  of  Georgia  or  Florida  long- 
leaf  yellow  pine  of  such  quality  as  shall  satisfy  the  requirements 
of  Standard  Inspection  according  to  the  Interstate  Rules  of  1905. 

They  shall  be long, thick,  and in  width.  Ties  shall 

be  sawed  or  hewn  smooth  on  four  sides,  with  the  faces  true  and 
parallel;  free  from  deep  score  marks,  splinters,  and  other  inju- 
rious inequalities  of  surface;  and  shall  be  sawed  square.  The 
variation  in  thickness  shall  not  be  more  than  one-half  inch,  and  in 
length  not  more  than  1  inch.  Ties  shall  be  treated  with  dead 


301 


82  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

oil  of  coal  tar  and  each  tie  after  treatment  must  contain  not 
less  than  10  pounds  of  oil  per  cubic  foot. 

Switch  Ties.  All  switch  ties  shall  be  of  Georgia  or  Florida 
long-leaf  yellow  pine  of  such  quality  as  shall  satisfy  the  require- 
ments of  Standard  Inspection  according  to  the  Interstate  Rules 
of  1905.  Switch  ties  shall  be  treated  with  dead  oil  of  coal  tar, 
and  each  piece  after  treatment  must  contain  not  less  than  10 
pounds  of  oil  per  cubic  foot. 

Treatment.  Steaming.  It  is  preferred  that  the  timber  shall 
be  thoroughly  air  seasoned  for  90  days  before  treating ;  that  which 
is  not  thoroughly  seasoned  shall  be  steamed.  To  obtain  the 
removal  of  sap  and  water  and  to  open  the  pores  of  the  wood, 
the  timber  shall  be  subjected  to  the  direct  action  of  live  steam 
admitted  to  the  treating  cylinder  under  a  pressure  of  not  less 
than  20  pounds  and  not  to  exceed  30  pounds  p'er  square  inch,  as 
recorded  by  a  steam  gage  attached  to  the  treating  cylinder 
(which  pressure  must  be  sustained  within  the  cylinder  for  from 
30  to  50  minutes).  The  pressure  and  time  of  steaming  shall  be 
regulated  according  to  the  size  and  condition  of  the  stock  used. 
The  time  of  steaming  shall  range  from  2  to  6  hours,  depending 
on  the  character  and  condition  of  the  timber.  The  cylinder  shall 
be  frequently  drained  by  a  valve  located  at  its  lowest  point. 
The  timer  used  in  any  one  cylinder  charge  shall  all  be  of  the  same 
class,  kind,  and  quality;  that  is  to  say,  any  one  cylinder  charge 
shall  be  exclusively  long-leaf,  short -leaf,  or  loblolly  pine,  and 
in  no  case  shall  these  be  mixed. 

Injection.  "When,  in  the  opinion  of  the  Engineer,  the  timber 
shall  have  undergone  the  steaming  process  for  a  sufficient  length 
of  time,  a  vacuum  shall  be  created  in  the  cylinder,  the  tempera- 
ture being  at  all  times  maintained  above  the  boiling  point.  A 
vacuum  of  from  22  to  26  inches  shall  continue  for  from  1  to  6 
hours,  or  until  the  timber  has  been  thoroughly  seasoned  and 
no  sap  or  moisture  comes  from  or  remains  in  the  cylinder.  During 
this  vacuum  process  the  lumber  in  the  cylinder  shall  be  kept  at 
a  temperature  of  about  175°  F.  by  means  of  steam  coils  in  the 
cylinder.  "While  the  above  vacuum  is  maintained,  the  oil,  as 
herein  specified,  shall  be  admitted  to  the  cylinder  under  pressure 
at  a  temperature  of  at  least  175°  F.  and  the  pressure  pump  shall 
be  kept  in  operation  until  the  timber  has  absorbed  the  pre- 
scribed amount  of  oil  per  cubic  foot,  the  same  to  be  determined 
by  such  system  of  measurements  and  tests  as  the  Engineer  shall 
elect.  When  the  cylinder  is  nearly  full,  the  valve  leading  to  the 
vacuum  pump  shall  be  closed  and  the  oil  slowly  forced  into  the 
cylinder  and  the  pressure  maintained  until  the  wood  has  absorbed 
the  required  amount. 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  83 

If,  in  the  judgment  of  the  Inspector,  a  better  and  more 
satisfactory  treatment  can  be  obtained  by  breaking  the  vacuum 
before  filling  the  cylinder  with  the  creosote  oil,  and  then  forcing 
the  oil  into  the  wood  with  pressure,  the  Inspector  shall  have  the 
power  to  order  such  method  of  injecting  with  creosote  oil.  This 
is  not  intended  to  obviate  or  relieve  the  necessity  of  applying 
the  final  air  pressure  as  hereinafter  provided. 

After  releasing  the  pressure  and  emptying  the  cylinder  of  oil, 
air  pressure  in  excess  of  the  oil  pressure  shall  be  applied,  to 
render  the  penetration  more  perfect  and  make  the  outside  of 
the  timber  cleaner  and  drier. 

The  entire  charge  of  timber  shall  absorb  the  oil  to  a  depth 
of  not  less  than  2  inches  on  all  exposed  surfaces.  Such 
pieces  as  fail  to  receive  the  required  penetration  shall  be  re- 
turned to  the  chamber  with  a  subsequent  charge  for  further 
treatment. 

Oil.  The  oil  used  in  treatment  shall  be  a  dead  oil  of  coal  tar 
commonly  known  as  creosote  oil,  and  shall  be  the  best  obtainable 
grade  of  coal  tar  creosote.  Its  specific  gravity  shall  not  be  less 
than  1.04  at  35°  C.  It  shall  not  contain  more  than  2$%  of 
water.  Compensation,  by  the  injection  of  a  proportionately  larger 
amount  of  oil  into  the  timber  being  treated,  for  a  greater  amount 
of  water  in  the  oil  will  not  be  allowed.  The  oil  shall  be  com- 
pletely liquid  at  38°  C.  and  must  be  free  from  suspended 
matter.  It  shall  yield  not  more  than  10%  by  weight  when  dis- 
tilled up  to  210°  C.  Between  210°  and  235°  C.,  the  dis- 
tillate by  weight  shall  not  be  less  than  25  %  or  more  than  30%, 
and  at  least  3Q%  weight  shall  not  distill  below  260°  C.  The 
oil  must  be  free  from  acetic  acid  and  acetates,  and  the  residue 
above  355°  C.,  if  it  exceeds  5$  in  quality,  must  be  soft. 
The  sample  of  oil  for  test  shall  be  taken  from  the  side  and  near 
the  middle  of  the  treating  cylinder,  after  the  pump  has  begun 
the  injection  of  oil.  During  the  analysis  of  the  oil,  the  ther- 
mometer bulb  shall  be  kept  about  one-eighth  of  ah  inch  above  the 
surface  of  oil  in  the  retort. 

Loading.  The  timber  shall  be  piled  on  the  treating  trucks  in 
such  manner  as  to  give  all  sides  of  the  timber  access  to  the  creo- 
sote oil.  All  pieces  treated  in  any  one  cylinder  load  shall  be  of 
uniform  character  and  sectional  dimensions.  Both  the  outside 
and  inside  bark  shall  be  carefully  removed  from  all  piling  before 
it  is  placed  in  the  treating  cylinder.  If  any  of  the  timber,  fur- 
nished under  contract,  is  acceptable  to  the  purchaser  and  con- 
tains less  than  the  prescribed  amount  of  dead  oil  of  coal  tar  per 
cubic  foot,  the  Contractor  agrees  to  make  an  allowance  on  each 
piece  of  timber  equal  to  the  difference  in  the  quantity  of  oil 


303 


84          CIVIL  SPECIFICATIONS  AND  CONTRACTS 

contained  in  each  piece  and  the  prescribed  amount  per  cubic 
foot  at  the  rate  of  ten  (10)  cents  per  gallon. 

Inspection.  The  timber  before  treatment  and  the  method  of 
treatment  shall  be  subject  to  the  inspection  of  such  inspectors 
as  shall  be  appointed  by  the  Purchaser,  and  he  shall  be  afforded, 
free  of  charge,  every  facility  for  performing  such  inspection. 
The  Contractor  shall,  upon  the  request  of  the  Inspector,  furnish 
the  Purchaser  with  samples  of  the  oil  being  used,  and  shall 
allow  the  Inspector  at  any  time  to  take  such  samples  of  oil  for 
testing  as  he  may  require.  The  Contractor  shall  grant  to  the 
Purchaser  or  his  inspectors  access  at  all  reasonable  times  to  all 
of  the  records  of  the  works  pertaining  to  the  treatment  of  timber 
for  the  Purchaser. 

The  Contractor  shall  provide  and  install  such  apparatus  as  is 
necessary  to  enable  the  Inspector  to  determine  the  amount  of 
oil  absorbed  by  the  timber,  this  amount  being  based  upon  gage 
readings  taken  before  the  introduction  of  the  oil  into  the  cylin- 
der and  after  the  forcing  back  of  the  oil  after  treatment;  also 
to  determine  the  various  temperatures  and  pressures  required, 
and  to  examine  the  products  of  the  vacuum. 

The  Inspector  shall'  be  allowed,  if  he  desires,  the  use  of  the 
laboratory  and  the  apparatus  therein  for  making  such  distilla- 
tion tests  as  he  may  require,  and  for  the  inspection  of  such  opera- 
tion in  connection  with  the  work. 

Should  he  desire  to  ascertain  the  depth  of  penetration  of  oil 
in  any  timber,  a  five-eighths-inch  auger  must  be  furnished  to  enable 
him  to  bore  such  timber,  and  he  shall  be  at  liberty,  if  he  so  desires, 
and  without  cost  to  the  Purchaser,  to  saw  in  two  one  tie  from 
each  500  ties  under  treatment,  to  ascertain  the  quality  of  the  work 
being  done. 

Inspection  and  acceptance,  or  lack  of  inspection  and  lack  of 
acceptance  or  rejections,  on  the  part  of  the  Purchaser,  or  his 
inspectors,  shall  not  be  any  bar  to  subsequent  rejection  for  cause. 

Method  of  Distillation.  In  making  the  tests  the  oil  shall  be 
distilled  according  to  the  common  method;  that  is,  using  an 
8-ounce  asbestos-covered  retort  with  standard  thermometer  bulb 
one-half  inch  above  the  surface  of  the  oil ;  the  creosote  calculated  on 
the  basis  of  the  dry  oil  shall  give  the  distillates  as  above  required 
at  the  various  temperatures. 

IRON  WORK  FOR  TIMBER  TRESTLES 

Iron  Work.  All  bolts  and  nuts  shall  be  of  wrought  iron. 
Wrought  iron  shall  be  double  rolled,  of  the  best  quality  of  Amer- 
ican refined  iron,  tough,  fibrous,  ductile,  and  capable  of  standing 


304 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  85 

a  tensile  strain  of  48,000  pounds  per  square  inch  before  rup- 
ture, and  an  elpngation  of  22r/f  in  8  inches,  with  fracture 
wholly  fibrous.  It  shall  bend  cold  with  the  fiber  through  180° 
around  a  diameter  not  greater  than  twice  the  thickness  of  the 
specimen  tested,  without  fracture  on  the  outside  of  the  bent 
portion.  When  nicked  and  bent,  the  fracture  shall  show  at  least 
90%  fibrous. 

Cast  Iron.  All  castings  shall  be  tough,  close-grained  gray 
iron,  sound,  smooth,  clean;  free  from  cold  shuts,  blowholes, 
blisters,  and  all  defects;  and  shall  be  made  accurately  to  the 
dimensions  shown  on  the  plans.  Sample  pieces,  1  inch  square, 
cast  from  the  same  heat  of  metal  in  sand  molds,  shall  be  capable 
of  sustaining,  on  a  clear  span  of  12  inches,  a  central  load  of 
2400  pounds  when  tested  in  the  rough  bar.  A  blow  from  a 
hammer  shall  produce  an  indentation  on  a  rectangular  edge  of 
the  casting  without  flaking  the  metal. 

Cast  Washers.  Cast  washers  shall  be  of  cast  iron.  The  diam- 
eter shall  be  not  less  than  3^  times  the  diameter  of  the  bolt  for 
which  it  is  used,  and  its  thickness  shall  be  equal  to  the  diameter 
of  the  bolt ;  the  diameter  of  the  hole  shall  be  one-eighth  inch  larger 
than  the  diameter  of  the  bolt. 

Wrought  Washers.  Wrought  washers  shall  be  of  wrought 
iron  or  steel;  the  diameter  shall  be  not  less  than  3^  times  the 
diameter  of  the  bolt  for  which  it  is  used,. and  not  less  than  one- 
fourth  incli  thick.  The  hole  shall  be  one-eighth  inch  larger  than  the 
diameter  of  the  bolt. 

Bolts.  Bolts  shall  be  made  with  square  heads,  standard  size, 
the  length  of  the  thread  to  be  2£  times  the  diameter  of  the  bolt. 
The  nuts  shall  be  made  square,  standard  size,  with  threads  fit- 
ting closely  the  thread  of  the  bolt.  All  threads  shall  be  cut 
according  to  the  United  States  standard.  Drift  bolts  shall  have 
square  heads  and  chisel  points. 

Spikes.  Steel  wire  spikes  may  be  used  up  to  a  length  of  6 
inches ;  where  greater  lengths  are  required,  wrought  iron  or  steel 
shall  be  used. 

TRACK  LAYING 
HANDLING  SUPPLIES 

Work  to  Be  Performed.  The  work  to  be  performed  will 
consist  of  furnishing  all  material  (except  rails,  angle  bars,  bolts, 
frogs,  mates,  switches,  spikes,  and  electrical  bonds  and  ties, 
which  will  be  furnished  by  the  railroad  company,  f.  o.b.  cars  on 

siding  at'_. ),  all  tools,  machinery,  and  apparatus; 

the  doing  of  all  the  work  necessary  for  the  efficient  construction 


305 


86  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

of  a  railroad  with  passing  sidings,  as  called  for  by  these  speci- 
fications and  the  requirements  of  the  Engineer;  and  in  accord- 
ance with  the  plans  and  drawings,  leaving  the  whole  work  in  a 
finished  and  perfect  condition  in  every  respect,  from  a  point 
near at on  the Rail- 
road, known  as  station ,  to  a  point  in 

,    near    the ,    as    located    over    the 

right  of  way  of  said  railroad  company  for  a  distance  of 
miles. 

Delivery  of  Materials.    The  railroad  company  will  furnish  the 

material  above  specified,  f.  o.  b.  cars  on  siding  at - 

Upon  the  arrival  of  the  carloads  of  material,  the  railroad  com- 
pany will  turn  over  to  the  Contractor  the  bills  of  lading  covering 
the  material,  and  the  Contractor  will  then  be  held  responsible 
for  the  inspection  as  to  count  and  accounting  for  the  material. 

Unloading  Cars.  The  Contractor  will  be  required  to  remove 
from  the  cars,  promptly  on  their  arrival,  all  material,  and  will 
be  held  responsible  for  any  demurrage  arising  from  his  failure 
promptly  to  remove  the  material  from  said  cars.  The  materials 
shall  be  piled  in  such  a  manner  and  at  such  points  as  the 
Engineer  shall  prescribe. 

Sub-Delivery.  The  Contractor  will  be  required,  at  his  own 
cost  and  expense,  to  furnish  and  provide  all  labor  and  appliances 
required  for  handling  and  sub-delivery  of  all  materials  furnished 
him  by  the  Company. 

Material  on  Hand.  The  Contractor  must  at  all  times  keep 
such  a  record  of  materials  on  hand,  and  of  their  location,  that 
he  will  know  whether  he  is  supplied  with  sufficient  material  to 
complete  the  work  in  accordance  with  the  specifications,  as  no 
additional  time  will  be  allowed  the  Contractor  to  complete  his 
work  by  reason  of  his  learning  at  too  late  a  time  that  additional 
material  is  required  to  complete  the  work  within  the  time  speci- 
fied. All  materials  delivered  along  the  line  of  the  proposed  rail- 
road before  the  completion  of  the  grading  shall  be  placed  outside 
the  line  of  the  slope  stakes. 

PREPARING  ROADBED 

Grading.  Before  a  tie  is  laid,  and  just  before  the  track  laying 
is  begun,  a  small  gang  of  experienced  graders  shall  go  ahead  of 
the  tie  layers  with  the  engineer  corps,  who  will  give  the  grades 
and  the  superelevation  of  the  curves. 

The  graders,  in  charge  of  a  competent  foreman,  must  be  pro- 
vided with  the  necessary  sight  boards,  and  other  tools  and  imple- 
ments required,  and  must  carefully  level  off  the  surface  of  the 


306 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  87 

roadbed  to  the  grade  stakes  set  for  same,   and  no  indifferent 
leveling  of  gradir.g  will  be  allowed. 

No  blocking  up  under  crossties,  with  timber  or  broken  rock, 
will  be  allowed. 

LAYING  THE  TRACK 

Ties.  The  ties  shall  be  spaced  so  as  to  give  16  ties  to  each 
33  feet  of  rail.  At  rail  joints  the  ties  shall  be  spaced  18  inches 
between  centers.  On  tangents  they  shall  be  laid  truly  at  right 
angles  to  the  rails,  while  on  curves  they  shall  be  laid  radially, 
and  the  ends  lined  up  parallel  with  the  rails  on  the  side  of  the 
track  which  the  Engineer  may  direct.  The  ties  must  not  be 
notched  under  any  circumstances,  but  should  they  be  twisted, 
they  must  be  made  true  with  the  adz,  in  order  that  the  rails 
may  have  an  even  bearing  over  the  whole  breadth  of  the  tie. 

Rails.  Bending.  If  the  rails  are  bent  in  handling  they  shall 
be  perfectly  straightened  before  being  laid  in  the  track.  Rails 
used  on  sharp  curves  shall  be  curved  in  a  bending  machine  accu- 
rately and  truly  to  ordinates,  which  will  be  furnished  by  the 
Assistant  Engineer.  In  no  case  will  forcing,  springing,  or  sledging 
the  rails  be  allowed. 

Laying.  To  avoid  bad  joints  and  short  rails,  the  track  laying 
shall  proceed  from  the  ends  of  the  road  and  it  shall  be  continuous 
for  the  entire  length  of  the  same.  The  rails  shall  be  laid  to  the 
stakes  given  by  the  Engineer,  and  on  curves  they  must  be  bent 
to  the  proper  curvature  before  being  laid  upon  the  ties.  On 
tangents  the  rails  shall  be  level,  and  on  curves  the  proper  eleva- 
tion must  be  given  to  the  outer  rail  and  carried  uniformly  around 
the  curve.  This  elevation  shall  be  commenced  from  50  to  200 
feet  back  of  the  point  of  curvature  as  directed  by  the  Engineer 
and,  depending  on  the  degree  of  the  curve,  shall  be  increased 
uniformly  to  the  latter  point,  where  the  full  elevation  is  attained. 
On  curves  sharper  than  4  degrees,  an  additional  spike  shall  be 
put  on  the  outside  of  the  outer  rail. 

Spiking.  There  must  be  four  spikes  to  each  crosstie — two 
inside  and  two  outside  of  the  rails ;  they  must  be  driven  with  a 
proper  amount  of  "stagger",  so  as  to  avoid  splitting  the  cross- 
tres ;  and  the  two  inside  spikes  must  be  driven  in  the  same  edge 
of  tie,  so  as  to  keep  the  tie  at  right  angles  to  the  track.  In 
driving  spikes  on  the  gage  side,  care  must  be  taken  to  place  the 
gage  at  right  angles  with  the  rail.  The  spikes  must  be  driven 
as  nearly  perpendicularly  as  possible ;  and  not  more  than  4  inches 
from  center  to  center  of  spike  on  a  line  parallel  with  the  rail; 
and  no  blow  must  be  struck  after  the  head  of  the  spike  is  fairly 
down  on' the  rail  flange.  Great  care  must  also  be  taken  not  to 


307 


88  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

strike  the  rail,  and  none  but  experienced  and  expert  spikers  must 
be  employed  on  the  work. 

Joints.  The  joints  of  the  rails  shall  be  exactly  at  the  middle 
of  the  joint  ties,  and  the  joint  on  the  one  line  of  rail  shall  be 
opposite  the  middle  of  the  rail  on  the  other  line  of  rail  of  the 
same  track.  A  distance  must  be  left  between  the  ends  of  the 
rails  to  allow  for  expansion;  in  winter  five-sixteenths  of  an  inch. 
in  summer  one-sixteenth  of  an  inch.  The  use  of  iron  shims  for 
securing  this  spacing  will  be  imperatively  insisted  upon,  and  tin- 
Contractor  must  provide  himself  with  a  sufficient  quantity  of  them. 
of  the  thickness  above  specified.  Joints  on  or  within  4  feet  of 
cattle  guards  or  open  culverts  must  be  avoided  wherever  possible. 
Care  must  be  taken  to  place  the  angle  bars  squarely  in  position. 
The  head  of  the  bolts  must  be  struck  with  a  2-pound  hammer,  while 
pressure  is  applied  with  a  30-inch  wrench  to  tighten  the  bolt.  The 
gage  of  the  track  shall  not  vary  more  than  one-sixteenth  of  an  inch 
from  the  standard  of  this  railroad,  which  is  4  feet  8^  inches.  The 
gage  shall  be  widened  on  curves,  if  directed  by  the  Engineer, 
but  not  otherwise.  Such  elevation  shall  be  given  to  the  outer 
rail  on  curves  as  the  Engineer  shall  direct. 

Bonding.  All  the  joints  of  the  track  rails  shall  be  single 
bonded  with  the  Improved  Open  Double  Electric  Protected  Rail 
Bonds  having  a  capacity  equal  to  No.  0000  B.  &  S.  gage  round 
copper  wire. 

The  rail  drilling  to  receive  the  bonds  must  be  performed  on 
the  ground  and  all  holes  carefully  cleaned  out  and  the  bond 
terminals  thoroughly  polished  so  as  to  form  a  perfect  contact 
of  the  entire  circumference  of  the  terminal  of  the  bond  with 
the  rail.  Care  must  be  taken  not  to  disturb  the  bond  after  it  is 
put  in  place. 

Special  Work.  In  laying  switches,  frogs,  mates,  and  other 
special  work,  care  shall  be  taken  to  place  them  accurately  in  the 
position  determined  by  the  Engineer.  The  gage  at  switches,  on 
tangent,  shall  be  one-sixteenth  of  an  inch  tight.  If  the  special  work 
does  not  appear  to  fit,  no  attempt  whatever  shall  be  made  to  force 
it,  except  by  direction  of  the  Engineer.  Special  work  shall  be 
laid  on  ties  specially  provided  for  the  purpose,  which  shall  be 
so  laid  as  to  give  a  firm  and  a  continuous  bearing  upon  the 
ballast.  Particular  attention  should  be  given  to  having  them 
well  lined  up  to  avoid  low  joints  at  the  head  blocks  of  switches. 
Guard  rails  shall  be  used  on  curves  sharper  than  9  degrees,  and 
at  turnouts;  they  shall  be  of  proper  length,  and  properly  ad- 
justed and  securely  fastened.  Plans  of  switch  stands,  frogs,  and 
fixtures  will  be  furnished,  showing  minor  details  of  placing  in 
position,  etc.,  or  instructions  of  the  Engineer  shall  be  followed. 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  89 

Joints  Tightened.  After  the  surfacing  has  been  completed 
the  joints  shall  be  carefully  gone  over  and  tightened  up  as 
described  under  "Joints". 

Maintenance  Before  Acceptance.  Before  any  construction 
car  or  engine  is  allowed  to  run  over  the  rails,  the  track  must 
be  lined  and  so  firmly  tamped  to  a  good  level  that  there  shall  be 
no  chance  of  straining  or  bending  the  rails.  Material  for  tamping 
must  not  be  dug  out  of  embankments  or  bermes,  nor  shall  any 
material  be  taken  from  the  side  slopes  of  cuts  in  such  way  as  to 
disfigure  them.  When  track  material  is  being  hauled  by  the 
Contractor's  trains  over  track  already  laid,  such  track  shall  be 
kept  in  good  line  and  surface  by  the  Contractor.  The  Contractor 
shall  maintain  and  keep  the  track  in  good  repair  until  the  same 
is  accepted,  and  no  length  of  track  shall  be  accepted  and  taken 
off  the  hands  of  the  Contractor,  except  at  the  option  of  the 
Engineer,  until  the  whole  shall  have  been  completed. 

Measurement  of  Track  for  Payment.  In  making  payment  for 
track  laying,  all  measurements  shall  be  made  per  linear  foot  of 
single  track,  measured  on  the  center  line;  and  where  turnouts 
occur  the  measurement  shall  be  made  once  on  the  main  track 
and  again  011  the  turnout  from  the  point  of  switch  of  the  turn- 
out to  be  measured.  At  steam  or  electric  road  crossings,  measure- 
ments shall  be  made  once  on  the  main  track  and  again  on  the 
line  of  the  intersecting  road.  The  price  for  track  laying  shall 
include  the  unloading  and  hauling  of  materials;  the  placing  of 
ties,  rails,  angle  bars,  and  special  work;  and  the  bending,  bolting, 
spiking,  lining,  and  ballasting  of  the  same. 

BALLASTING 

Gravel  Ballast.  Gravel  shall  be  clean,  free  from  clay,  earth, 
loam,  and  stones  larger  than  would  pass  through  a  2i-inch  ring 
in  any  direction ;  it  must  not  contain  more  than  one-third  sand,  and 
shall  be  subject  to  the  inspection  and  acceptance  of  the  Engineer. 

Cinder  Ballast.  Cinder  ballast  shall  be  free  from  all  objection- 
able materials  and  of  a  quality  approved  by  the  Engineer. 

Broken  Stone.  Stone  ballast  shall  consist  of  clean  broken 
granite,  trap,  or  other  hard  stone,  to  be  approved  by  the  Engi- 
neer, and  must  be  crushed  so  that  its  greatest  dimension  will 
pass  through  a  2^-inch  ring. 

Lining.  After  the  rails  have  been  spiked  to  the  ties,  the 
entire  track  must  be  raised  to  the  finished  grade  and  carefully 
aligned  to  the  stakes  given  by  the  Engineer.  The  space  under 
the  ties  must  then  be  filled  with  ballast  of  approved  quality, 
satisfactory  to  the  Engineer.  Care  must  be  taken  in  raising  the 


309 


90  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

tcack  and  tamping  same  not  to  deform  the  rails,  splice  bars,  or 
bonds.  The  space  between  the  ties  shall  be  filled  with  ballast 
to  the  lines  and  slopes  as  shown  on  the  standard  section  of 
roadbed. 

Tamping.  The  ties  shall  be  tamped  from  15  inches  inside  the 
rail  to  the  ends  of  the  ties;  if  possible,  tamp  the  ends  of  the  tie 
outside  the  rail  first  and  allow  the  material  train  to  pass  over 
it  before  tamping  the  inside  of  the  rail,  giving  special  attention 
to  tamping  under  the  rail;  tamp  the  center  of  the  tie  loosely 
with  a  shovel  when  using  gravel  or  cinder  ballast;  where  stone 
ballast  is  used,  do  not  tamp  the  center  of  the  tie.  Ties  must  be 
tamped  solidly  from  the  end,  using  tamping  bar  or  tamping  pick, 
as  the  Engineer  may  direct.  Care  must  be  taken  not  to  disturb 
the  roadbed.  When  gravel  ballast  is  used  it  shall  be  firmly 
packed  or  rammed  between  the  ties  to  the  prescribed  slope,  so 
that  it  will  readily  shed  the  water  and  shall  not  be  banked  above 
the  bottom  of  the  ends  of  the  ties ;  a  space  of  not  iess  than  1  inch 
shall  be  left  between  the  top  of  the  ballast  and  the  base  of  the 
rail  to  allow  the  water  to  run  off  readily,  care  being  taken  to 
carry  the  ballast  in  the  middle  of  the  track  to  the  full  height 
shown  in  the  standard  drawings. 

SURFACING 

Every  care  shall  be  taken  to  maintain  the  crown  of  the  road- 
bed in  the  center  as  shown  on  the  standard  drawings  and,  when 
the  condition  of  the  roadbed,  on  account  of  washing  or  settle- 
ment, does  not  allow  of  the  exact  depth  of  ballast  beneath  the 
ties,  the  Contractor  shall  make  the  necessary  excavation  or  fill 
without  cost  to  the  Company.  Should  any  material  for  ballast 
be  taken  out  of  the  side  slopes  of  cuts,  it  must  be  done  in  such  a 
way  as  not  to  disfigure  them.  Material  for  ballast  shall  not  be 
taken  from  embankments.  In  surfacing,  the  level  board  shall  be 
used,  at  head,  at  joints,  at  quarters,  and  at  centers.  After  the 
completion  of  surfacing,  all  materials  that  shall  have  been  allowed 
to  accumulate  in  the  ditches  on  either  side  of  the  roadbed,  shall 
be  removed,  and  the  road  properly  ditched  and  cleaned  up.  All 
necessary  cross  drains  shall  be  laid  at  proper  intervals. 

GENERAL   SPECIFICATIONS    FOR   CROSSTIES 

Timber.  Crossties  will  be  accepted  of  the  following  varieties 
of  timber:  Oaks  of  the  various  kinds  known  as  white,  rock,  and 
post  (no  red  oak  will  be  received),  second  growth  white  chestnut, 
cherry,  maple,  butternut,  tamarack,  and  yellow  pine  -of  the  long- 


310 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  91 

leaf,  Southern  hard-pine  variety,  cut  from  untapped  trees  and 
grown  not  north  of  South  Carolina. 

Sizes.  First  Class.  First  class  crossties  shall  be  8£  feet  in 
length,  7  inches  in  thickness,  and  not  less  than  7  inches  In  width 
of  face  on  both  sides  at  the  small  end. 

Second  Class.  Second  class  crossties  shall  be  8  feet  in  length, 
6  inches  in  thickness,  and  not  less  than  6  inches  in  width  of  face 
011  both  sides  at  the  small  end;  and  in  each  class  there  must  be  at 
least  one-fourth  of  the  whole  number  that  are  not  less  than  9 
inches  in  width  of  face. 

Manufacture.  All  ties  must  be  made  from  sound,  thrifty,  live 
or  green  timber;  free  from  loose  or  rotten  knots,  wormholes,  dry 
rot,  wind-shakes,  splits,  or  any  other  imperfections  affecting  the 
strength  or  durability  of  the  timber. 

Not  more  than  1  inch  of  sapwood  will  be  allowed  on  the  edges 
or  corners,  and  none  at  all  on  either  face  of  the  ties.  They  must 
be  hewed  or  sawred  with  the  faces  perfectly  true  and  parallel, 
of  the  exact  thickness  specified.  The  faces  must  be  "out  of 
wind",  smooth,  and  free  from  any  inequalities  of  surface,  deep 
score  marks,  or  splinters.  The  ties  must  be  cut  or  sawed  square 
on  the  ends  to  the  exact  lengths  given;  they  must  be  generally 
straight  in  all  directions;  and  they  will  not  be  accepted  if  more 
than  3  inches  out  of  straight  in  any  direction;  and  they  must 
be  peeled  or  stripped  entirely  free  from  the  bark  before  being 
delivered.  No  split  ties  will  be  accepted  under  any  circum- 
stances, and  "culls"  only  at  the  option  of  the  Company  and  at 
such  prices  as  may  be  agreed  upon  from  time  to  time. 

Delivery.  All  ties  delivered  along  the  line  of  the  railway 
must  be  stacked  up  in  neat  square  stacks  of  50  ties  in  each,  with 
alternate  layers  crossing  each  other,  and  on  ground,  wherever 
possible,  as  high  or  higher  than  the  grade  of  the  railroad,  and  in 
such  position  as  to  admit  of  being  counted  and  inspected  with 
ease  and  facility.  Ties  delivered  at  suitable  and  convenient 
places,  acceptable  to  the  Company,  will  be  inspected,  and  bills 
made  for  all  ties  received  and  accepted  up  to  the  last  day  of 
each  month,  and  payment  will  be  made  for  same  on  or  about  the 
day  of  the  succeeding  month. 


311 


CIVIL   ENGINEERING    SPECIFICA- 
TIONS AND  CONTRACTS 


PART  II 


TYPICAL  ILLUSTRATIVE  SPECIFICATIONS 

( Continued  J 

SPECIFICATIONS  FOR  OVERHEAD  CONSTRUCTION 
OF  AN  ELECTRIC  RAILWAY 

Materials  Furnished  by  the  Company.  The  Company  will 

furnish  f.  o.  b.  cars City,  all  poles  and  trimmings, 

span  wire,  trolley  wire,  and  overhead  construction  materials 
with  the  exception  of  solder,  tape,  and  paint. 

Contractor's  Obligations.  The  Contractor  shall  remove  from 
railroad  stations  all  poles  and  overhead  materials,  and  shall  store 
and  protect  same,  and  be  responsible  for  their  safe  keeping.  The 
Contractor  shall  be  responsible  for  demurrage  accruing  from 
neglect  to  remove  the  materials  from  the  cars  promptly.  The 
Contractor  shall  furnish  all  labor,  tools,  and  appliances  for  the 
complete  erection  of  the  overhead  construction. 

Poles.  The  poles  shall  be  of  iron,  28  feet  long,  weighing 
approximately  600  pounds.  They  shall  be  made  of  7-,  6-,  and 
5-inch  section  of  pipe,  telescoped  and  swedged  together. 

Setting.  The  Company  will  furnish  permits  for  the  erection 
of  poles  located  as  shown  on  the  plans.  The  Contractor  shall  set 
poles  6  feet  in  the  ground  in  1-3-6  Portland  cement  concrete, 
in  holes  not  less  than  18  inches  in  diameter.  Poles  shall  be  set 
with  a  rake  of  8  inches,  on  straight  track,  away  from  the  line 
of  strain.  On  curves,  poles  shall  be  set  with  a  rake  of  14  inches. 
In  case  water  is  found  in  pole  holes,  the  lower  portion  of  the 
hole  must  be  protected  by  sinking  a  barrel,  or  by  other  similar 
precaution.  Before  poles  are  placed  in  concrete,  they  shall  be 
given  one  coat  of  approved  asphalt  paint  for  the  lower  7  feet. 
Asphalt  paint  shall  be  furnished  by  the  Contractor. 

All  pavements,  awnings,  water,  gas,  or  sewer  pipes,  or  other 
structures  damaged  during  the  erection  of  the  poles  must  be 

93 


313 


94  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

replaced  in  as  good  condition  as  found,  at  the  Contractor's 
expense. 

On  completion  of  work,  the  poles  shall  be  painted  with  one 
coat  of  lead  and  oil  paint,  of  approved  color.  The  paint  shall 
be  supplied  by  the  Contractor. 

Span  Construction.  The  entire  line  shall  be  of  span  con- 
struction. The  span  wires  shall  consist  of  seven-strand  five-six- 
teenths-inch  galvanized  steel  cable;  and  the  spans  shall  be  secured 
to  the  poles  by  double-bolt  pole  rings.  At  each  end  of  the  span  wire 
there  shall  be  put  in  a  globe  strain  insulator  which  shall  connect 
with  the  outer  bolt  of  the  pole  band.  The  spans  shall  be  drawn  taut 
and  the  ends  shall  be  made  up  to  the  strains.  At  all  curves  the 
pull-off  wires  shall  be  secured  to  an  anchor  pole  with  a  heavy 
band ;  a  turnbuckle  and  a  heavy  insulated  strain  shall  be  put  in 
between  the  pull-off  wires  and  the  pole.  Each  pull-off  wire  shall 
have  in  addition  to  this  insulation  a  giant  strain  insulator  at  the 
pull-off  fitting.  "Wherever  pull-off  wires  cross  the  main  trolley 
wire,  they  shall  be  secured  to  the  cross  wire  with  standard 
soldered  ear  and  bell  insulator. 

Trolley  Wire.  Trolley  wire  shall  be  No.  0000  B.  &  S.  gage 
round  copper  wire.  At  terminals  wire  shall  be  secured  to  poles 
through  heavy  double  strain  insulators-  and  bridled  to  terminal 
poles.  Trolley  wire  shall  be  strung  tight  and  shall  be  at  least  20  feet 
from  the  track,  except  at  railroad  crossings,  where  it  must  be  22 
feet  from  the  track.  At  each  side  of  all  railroad  crossings  there 
shall  be  installed  a  strain  ear  secured  to  an  extra  span  wire  run 
above  regular  span  wire,  with  globe  strain  insulation  in  the 
bridle.  Trolley  wire  must  be  located  in  the  true  center  of  the 
track  on  a  straight  track,  and  at  all  curves  it  must  be  so  pulled 
over  that  the  trolley  wheel  on  the  car  will  always  stay  on  the  wire. 

The  insulated  hangers  shall  be  the  Keystone  bell  type.  The 
ears  shall  be  deep-grooved  milled  ears,  soldered  to  the  wire. 
Great  care  must  be  used  in  soldering;  flux  used  shall  be  Yeager 
soldering  salt  or  its  equal. 

Frogs  and  Lightning  Arresters.  The  Contractor  shall  install 
all  of  the  necessary  frogs  over  special  work;  install  the  neces- 
sary insulated  crossings  at ---Avenue;  and  install  4 

lightning  arresters  attached  to  the  poles  and  the  necessary  single 
No.  0  B.  &  S.  gage  wire  in  connections  from  same  to  the  track. 
These  lightning  arrester  lead  wires  are  to  be  brought  down  inside 
the  pole,  through  a  hole  bored  in  the  pole  below  the  pave- 
ment line,  and  the  wires  shall  be  connected  to  the  cross  bond  in 
the  track  and  securely  soldered  to  the  same. 

Joints.  All  joints  in  the  trolley  wire  shall  be  made  with  long 
soldered-copper  sleeves. 


314 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  95 

Strain  Guys.     The  strain  guys  shall  be  erected  on  each  side 

of  the  curves  between Avenue  and 

Avenue,  leading  into Avenue.    Single  strain  guys 

shall  be  placed  on  each  side  of  each  railroad  crossing.  These 
strain  guys  shall  lead  to  the  nearest  poles  and  have  a  globe  strain 
insulator  cut  in,  2  feet  from  the  strain  ear,  and  also  at  turnbuckle. 

It  is  the  general  intention  of  these  specifications  that  the 
Contractor  shall  erect  the  complete  overhead  construction  ready 
for  the  operation  of  cars. 


SPECIFICATIONS  FOR  A  STONE  ROAD 

Work  to  be  Performed.  The  work  to  be  performed  will  con- 
sist in  furnishing  all  material,  tools,  machinery,  and  labor  neces- 
sary for  the  efficient  and  proper  grading  of  the  roadway,  side 
ditches,  and  side  banks;  for  the  laying,  spreading,  and  rolling 
of  road  metal ;  and  leaving  the  roadway  complete  in  every  manner, 
ready  for  immediate  use. 

Plans  and  Drawings.  The  plan,  profile,  and  cross  sections  on 
file  in  the  office  of  the  State  Commissioner  of  Public  Roads  and 

at  the  office  of County  Engineer, 

,  show  general  location,  profile,  details,  and  dimen- 
sions. The  work  will  be  constructed  in  all  respects  according  to 
the  above-mentioned  plans,  profile,  and  cross  sections,  which  form 
part  of  these  specifications. 

Any  variation  of  location,  profile,  size,  and  dimensions  from 
that  shown  on  the  plans,  as  may  be  required  by  the  exigencies 
of  construction,  will,  in  all  cases,  be  determined  by  the  Engineer ; 
but  the  Contractor  shall  not,  on  any  pretense,  save  that  of  the 
written  order  of  the  contracting  parties,  deviate  from  the  intent 
of  the  plans  or  specifications. 

On  all  drawings,  figured  dimensions  are  to  govern  in  cases  of 
discrepancy  between  scale  and  figures. 

Grading.  Under  this  head  will  be  included  all  the  excava- 
tion and  embankment  required  for  the  formation  of  the  highway ; 
cutting  all  ditches  or  drains  about  or  contiguous  to  the  road; 
removing  all  fences,  walls,  buildings,  trees,  poles,  or  other  encum- 
brances; the  excavation  and  embankment  necessary  for  recon- 
structing cross  or  branch  roads  in  cases  where  they  are  destroyed 
or  interfered  with  in  the  formation  of  the  roadway ;  and  all  other 
excavations  and  embankments  connected  with  or  incidental  to 
the  construction  of  the  said  road. 

Excavation.     The  roadway  to  the  width   of..... 
feet  as  shown  on  the  plan  must  be  excavated  or  built  to  the  same 


315 


96  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

curvature  as  that  of  the  surface  of  the  road  when  finished;  the 
grade,  from  center  to  sides,  must  be  as  shown  on  plans. 

The  earth  taken  from  any  cut  or  ditch  shall  be  deposited 
wherever  the  Engineer  may  direct,  either  within  or  without  the 
line  of  the  road ;  but  no  earth  shall  be  removed  from  the  line  of 
the  road  without  the  order  of  the  Engineer. 

The  grading  shall  be  completed  for  the  full  width  of  the  road, 
from  gutter  to  gutter,  before  any  macadamizing  is  commenced. 

Embankment.  Material  taken  from  the  excavations,  except 
when  otherwise  directed  by  the  Engineer,  shall  be  deposited  in 
the  embankments,  either  on  the  roadway  or  sidewalks.  Rejected 
or  excess  material  will  be  used  to  increase  the  width  of  the  em- 
bankments or  deposited  in  spoil  banks  or  waste  piles,  wherever 
and  however  the  Engineer  may  direct. 

"When  there  is  not  sufficient  material  in  the  excavations  of 
the  road  to  form  the  embankments,  the  deficiency  must  be  sup- 
plied by  the  Contractor  from  without  the  road;  the  character  of 
said  material  and  place  of  excavation  must  be  approved  by  the 
Engineer;  and  said  material  is  to  be  paid  for  at  the  same  price 
per  cubic  yard  as  specified  in  the  contract  for  other  excavation. 

The  embankments  will  be  formed  in  layers  of  such  depth, 
generally  1  foot,  and  the  material  deposited  and  distributed  in 
such  a  manner  as  the  Engineer  may  direct,  the  required  allow- 
ance for  settling  being  added. 

Slopes.  Slopes  in  both  embankments  and  excavations  shall 
be  1^  horizontal  to  1  vertical,  unless  otherwise  ordered  by  the 
Engineer. 

Roadbed.  Siibfoundation.  "When  the  excavations  and  em- 
bankments have  been  brought  to  a  proper  depth  below  the 
intended  surface  of  the  roadway,  the  cross  section  thereof  con- 
forming in  every  respect  to  the  cross  section  of  the  road  when 
finished,  the  same  shall  be  rolled  with  a  10-ton  steam  roller  until 
approved  by  the  Engineer.  If  any  depressions  form  under  such 
rolling,  owing  to  improper  material  or  vegetable  matter,  the 
same  shall  be  removed  and  good  earth  substituted,  and  the  whole 
shall  be  rerolled  until  thoroughly  solid  and  to  above-mentioned 
grade.  "Water  must  be  applied  in  advance  of  the  roller  when, 
in  the  opinion  of  the  Engineer,  it  is  necessary. 

Telford  Foundation.  After  the  subfoundation  has  been 
formed  and  rolled,  as  above  specified,  and  has  passed  the  inspec- 
tion of  the  Engineer,  a  bottom  course  of  stone,  of  an  average 
depth  of  10  inches,  is  to  be  set  by  hand  as  a  close  firm  pavement ; 
the  stones  shall  be  placed  on  their  broadest  edges  lengthwise 
across  the  road  in  such  a  manner  as  to  break  joints  as  much  as 
possible,  and  the  breadth  of  the  upper  edge  shall  not  exceed  4 


316 


CIVIL  SPECIFICATIONS  AND  CONTRACTS  97 

inches.  The  interstices  are  then  to  be  filled  with  stone  chips, 
firmly  wedged  by  hand  with  a  hammer,  and  projecting  points  shall 
be  broken  off.  No  stone  of  greater  length  than  10  inches  or  width 
of  4  inches  shall  be  used,  except  each  alternate  stone  on  the  outer 
edge,  which  shall  be  double  the  length  of  the  others  and  well  tied 
into  the  bed  of  the  road;  all  stones  with  a  flat  smooth  surface 
must  be  broken ;  the  whole  surface  of  this  pavement  shall  be  sub- 
jected to  a  thorough  settling  or  ramming  with  heavy  sledge 
hammers,  and  shall  be  thoroughly  rolled  with  a  10-ton  steam 
roller.  No  stone  larger  than  2|  inches  shall  be  left  loose  on  top 
of  telford. 

Macadam.  First  Course  of  Broken  Stone.  After  the  road 
bed  has  been  formed  and  rolled  as  above  specified,  and  has  passed 
the  inspection  of  the  Engineer,  the  first  layer  of  broken  stone, 
consisting  of  2|*-inch  stone,  or  stone  that  will  pass  through  a  ring 
3  inches  in  diameter,  shall  be  deposited  in  a  uniform  layer,  having 
a  depth  of  6  inches,  and  rolled  repeatedly  with  a  10-ton  steam 
roller  until  compacted  to  the  satisfaction  of  the  Engineer.  No 
stone  in  this  course  shall  be  less  than  2  inches  in  length.  Water 
must  be  applied  in  advance  of  the  roller,  when,  in  the  opinion 
of  the  Engineer,  it  is  necessary. 

The  depth  of  loose  stone  in  this  and  all  other  courses  must 
be  measured  by  blocks  the  required  thickness  of  the  said  loose 
stone.  These  blocks  shall  be  placed  at  frequent  intervals  amid 
the  loose  stone  when  being  spread. 

Binder  Between  First  and  Second  Course.     On  the  first  course 

of  stone  a  quantity  of binder  shall  be  spread  in  a 

uniform  layer,  and  the  rolling  shall  be  continued  until  the  stones 
cease  to  sink  or  creep  in  front  of  the  roller ;  water  will  be  applied 
in  advance  of  the  roller,  if  ordered  by  the  Engineer.  The  quan- 
tity and  quality  of  this  and  all  other  binding  shall  be  at  all  times 
subject  to  the  approval  of  the  Engineer. 

Second  Course  of  Broken  Stone.  The  second  course  of  broken 
stone  shall  consist  of  1^-inch  stone ;  that  is,  every  piece  of  stone 
shall  be  broken  so  that  it  can  be  passed  through  a  ring  2  inches 
in  diameter,  and  no  stone  shall  be  more  than  2  inches  nor  less 
than  1  inch  long.  This  course  is  to  be  spread  in  a  uniform  layer 

of inches  in  depth,  and  rolled  until  thoroughly  settled 

into  place  to  the  satisfaction  of  the  Engineer.  Water  will  be 
applied,  if  ordered  by  the  Engineer. 

Binder  on  Second  Course  of  Stone.  Binder  on  this  course  of 
stone  must  be  applied  in  the  manner  already  given  for  binder  on 
first  course  of  stone  as  directed  by  Engineer. 

Surface.  When  the  two  courses  are  rolled  to  the  satisfaction 
of  the  Engineer,  a  coat  of  50  per  cent  of  three-fourths-inch  stone 


317 


98  CIVIL  SPECIFICATIONS  AND  CONTRACTS 

and  50  per  cent  of  screenings,  properly  mixed,  is  to  be  spread  of 
sufficient  thickness  to  make  a  smooth  and  uniform  surface  to  the 
road;  then  the  road  shall  again  be  rolled  until  it  becomes  thor- 
oughly consolidated,  hard,  and  smooth. 

Rolling  shall  be  done  by  the  Contractor  with  a  10-ton  roller, 
approved  by  the  Engineer. 

Any  depressions  formed  during  the  rolling,  or  from  any  other 
cause,  are  to  be  filled  with  l^-inch  stone  or  three-fourths-inch  stone, 
or  both,  and  screenings  approved  by  the  Engineer,  and  the  road- 
way shall  be  brought  to  the  proper  grade  and  curvature  as  deter- 
mined by  him. 

Water  must  be  applied  in  such  quantities  and  in  such  manner 
as  directed  by  the  Engineer. 

Manner  of  Rolling.  In  the  rolling,  the  operator  must  start 
from  the  side  lines  of  the  stone  bed  and  work  towards  the  center, 
unless  otherwise  directed.  The  rolling  shall  at  all  times  be  under 
the  control  of  the  Engineer,  who  may,  from  time  to  time,  direct 
such  methods  of  procedure  as  in  his  opinion  are  required  by  the 
necessities  of  the  case. 

Quality  of  Material.  All  stone  must  be  as  nearly  cubical  as 
possible ;  broken  with  the  most  approved  modern  stone-crushing 
machinery;  free  from  all  screenings,  earth,  and  other  objection- 
able substances ;  of  uniform  size  and  of  the  same  kind  and  quality, 
or  of  a  kind  and  quality  equally  good  in  every  particular  as  that 
shown  in  the  Engineer's  office.  The  1^-inch  stone  or  three-fourths- 
inch,  and  the  screenings  for  binder  and  the  final  finish  must  be  of 
the  best  trap  rock,  and  must  be  free  from  loam  or  clay. 

The  Contractor  must  furnish  samples  to  the  Engineer  of  the 
kind  of  stone  to  be  used  in  the  work  before  the  opening  of  the  bids. 

Shouldering.  A  shoulder  of  firm  earth  or  gravel  is  to  be  left 
or  made  on  each  side,  extending  at  the  same  grade  and  curvature 
of  the  road  to  the  side  ditches  or  gutters.  This  shoulder  is  to  be 
rolled  according  to  the  directions  of  the  Engineer. 

Side  Ditches  or  Gutters.  The  side  ditches  or  gutters  are  to 
be  excavated  as  per  stakes  furnished  by  the  Engineer,  in  order 
to  give  an  easy  flow  of  water,  so  that  no  water  shall  be  left  stand- 
ing on  the  road  or  in  the  ditches ;  and  for  this  excavation  no  extra 
payment  will  be  made. 

Underdrains.  Underdrains,  if  found  necessary,  shall  be  con- 
structed by  the  Contractor  (at  prices  named  in  bids)  of  good 
4-inch  tile,  laid  upon  a  board  of  not  less  than  1  inch  in  thickness 
and  6  inches  in  width,  whenever  and  wherever  the  Engineer  and 
Supervisor  shall  decide ;  the  top  of  the  tile  shall  be  at  least 
inches  deep,  unless  otherwise  directed  by  the  Engineer; 


318 


CIVIL  SPECIFICATIONS  AND  CONTRACTS          99 

the  joints  of  the  tile  shall  be  covered  with  salt,  hay,  or  material 
equally  good;  and  the  trench  shall  be  filled  with  pervious  earth. 

When  directed  by  the  Engineer  a  stone  drain  may  be  used 
in  place  of  the  tile  drain.  A  trench  1  foot  wide  and  1  foot  6 
inches  in  depth  shall  be  excavated  below  the  subgrade,  said 
excavation  to  be  filled  with  loose  broken  stone  to  a  depth  required 
by  the  Engineer. 

No  Extra  Price.  No  allowance  in  measure  of  depth  of  pave- 
ment will  be  made  on  account  of  any  material  which  may  be 
driven  into  the  roadbed  by  rolling.  The  pavement  when  com- 
pleted must  conform  to  the  grade  and  the  cross  sections,  and  be 
satisfactory  to  the  Engineer,  whose  decision  shall  be  final. 

No  extra  work  will  be  paid  for  unless  the  price  has  been 
agreed  upon  between  the  contracting  parties,  including  the  State 
Commissioner  of  Public  Roads,  and  endorsed  upon  the  agreement, 
witnessed  by  the  Engineer. 

All  clay  or  gravel  for  shouldering  or  binder,  and  all  extra 
hauling,  is  to  be  done  at  the  Contractor's  expense. 

Broad  Tire  Wagons.  All  wagons  and  carts  used  during  the 
construction  for  hauling  stone,  earth,  or  any  other  material  must 
have  tires  not  less  than  3^  inches  in  width. 

Liabilities  of  Contractor.  Road  Repairs  for  One  Year.  The 
Contractor  shall  keep  the  finished  roadway  and  earthwork  in 
repair  for  the  period  of  1  year  from  the  date  of  its  completion 
and  acceptance,  during  which  time  he  shall  be  liable  for  the  wear 
and  tear  caused  by  ordinary  travel ;  and,  in  addition  thereto,  he 
shall  be  liable  for  as  much  longer  as  for  any  period  or  periods 
during  said  year  it  shall  be  out  of  proper  condition.  If,  during 
the  time  of  the  Contractor's  liability,  the  roadway  or  any  part  of 
the  work  shall,  in  the  judgment  of  the  Engineer,  require  repair- 
ing, and  he  shall  duly  notify  the  Contractor  to  make  such  repairs 
as  are  required ;  and  if  the  Contractor  shall  refuse  or  neglect  to  do 
so,  to  the  satisfaction  of  the  said  Engineer,  within  5  days  from 
the  date  of  the  service  of  the  notice,  then  the  said  Engineer 
shall  have  the  right  to  have  the  work  done  properly  by  other 
parties  and  pay  the  expense  for  the  same  out  of  the  5  per  cent 
retained. 

Preserving  Stakes  and  Bench  Marks.  The  Contractor  shall  be 
required  to  preserve  all  stakes  and  benchmarks  made  and  estab- 
lished on  the  line  of  work  until  duly  authorized  by  the  Engineer 
to  remove  the  same. 

Title  Stones.  The  Contractor  shall  not  disturb  the  position 
of  title  stones  (the  corners  of  properties  adjacent  to  the  road), 
but  where  they  appear  he  shall  either  lift  or  lower  them,  under 
the  personal  supervision  of  the  Engineer. 


319 


100         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Preserving  Clear  Roadway.  The  Contractor  must  also  pre- 
serve the  roadway  on  which  he  is  working  from  needless  obstruc- 
tion, and  where  necessary  he  must  construct  safe  and  commodi- 
ous crossings,  to  be  maintained  in  good  order.  He  shall  afford 
all  proper  and  reasonable  means  for  the  accommodation  of  the 
public,  and  leave  the  roadway  complete  in  every  manner,  ready 
for  immediate  use. 

Provision  for  Drainage.  If  it  is  necessary  in  the  prosecution 
of  the  work,  to  interrupt  or  obstruct  the  natural  drainage  of  the 
surface  or  the  flow  of  artificial  drains,  the  Contractor  shall  pro- 
vide for  the  same  during  the  progress  of  the  work  in  such  a  way 
that  no  damage  shall  result  to  either  public  or  private  interests. 
He  shall  be  held  liable  for  all  damages  which  may  result  from 
any  neglect  to  provide  for  either  natural  or  artificial  drainage, 
which  he  may  have  interrupted. 

Right  to  Build  Bridges,  Culverts,  etc.,  and  to  Suspend  Work. 
The  right  of  the  county  to  build  bridges,  culverts,  lay  pipes,  or 
other  appurtenances  in  said  road  during  the  progress  of  the  work 
is  expressly  reserved,  as  well  as  the  right  to  suspend  the  work 
or  any  part  thereof  during  the  construction  of  the  same,  for  the 
purposes  above  stated,  without  further  compensation  to  the  Con- 
tractor for  such  suspension  than  an  extension  of  time  for  com- 
pleting the  work  equal  to  the  length  of  time  his  work  may  have 
been  delayed. 

Stopping  Work  on  Account  of  Weather.  The  Engineer  may 
stop  any  portion  of  the  work  if,  in  his  judgment,  the  weather  is 
such  as  to  prevent  the  work  from  being  properly  done.  No 
allowance  of  any  kind  will  be  made  for  such  stoppage,  except  an 
extension  of  the  time  for  the  completion  of  the  work  as  herein 
provided. 

SPECIFICATIONS  FOR  CONCRETE  MACADAM 

Cement.  The  cement  shall  be  first-class  hydraulic  cement 
which  shall  conform  in  all  respects  to  the  Standard  Specifications 
of  the  American  Society  for  Testing  Materials.  All  cement  shall 
be  approved  in  writing  by  the  State  Highway  Commissioner, 
before  ordering,  and  shall  preferably  be  delivered  on  the  work 
in  barrels.  The  Contractor  shall  furnish  samples  of  the  cement 
to  the  State  Highway  Commissioner,  before  any  of  it  is  used  on 
the  work. 

Water.  Water  shall  be  fresh  and  clean,  free  from  earth, 
refuse,  and  injurious  mineral  matter. 

Broken  Stone.  Broken  stone  shall  be  good  hard  trap  rock 
or  hard  blue  limestone,  clean  and  sound,  broken  into  sizes  ranging 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         101 

from  one-half  inch  to  1£  inches  in  diameter.  It  must  be  thoroughly 
cleaned  of  refuse  before  using. 

Sand.  All  sand  shall  be  clean,  coarse,  sharp,  and  free  from 
loam  and  vegetable  matter. 

Concrete  Mixing.  This  concrete  shall  consist  of  the  above 
materials  properly  proportioned  for  a  1-3-5  mixture,  and  shall 
be  mixed  with  a  sufficient  quantity  of  water  to  cause  the  free 
mortar  to  rise  to  the  top  of  the  mass  of  concrete  when  tamped 
into  place.  It  shall  be  thoroughly  mixed  by  hand  or  machine 
and  to  the  satisfaction  of  the  State  Highway  Commissioner  or 
Engineer  in  charge. 

Placing.  After  the  roadbed  has  been  prepared  according  to 
these  plans  and  specifications,  a  layer  of  concrete,  proportioned 
as  specified  above,  shall  be  placed  to  a  depth  of  6  inches,  on 
one-half  the  width  of  the  roadway.  The  inside  edges  shall  be  a 
dovetailed  line  as  shown  on  the  accompanying  plans. 

Tamping.  The  concrete  shall  be  thoroughly  tamped  with  a 
25-pound  tamper,  until  free  mortar  appears  on  the  surface  to 
the  depth  of  1  inch.  The  roadway  shall  then  be  covered  with 
three-fourths-inch  screenings,  free  from  dust,  and  the  same  shall 
be  lightly  tamped  into  the  free  mortar  until  they  are  embedded 
for  three-fourths  of  their  depth. 

Expansion  Joints.  If  in  the  judgment  of  the  State  Highway 
Commissioner  or  Engineer  in  charge,  expansion  joints  are  re- 
quired, they  shall  be  formed  at  intervals  of  every  40  feet,  by 
placing  one-half-inch  by  8-inch  boards  in  the  concrete,  at  right 
angles  to  the  center  line  of  the  road.  These  boards  shall  be  properly 
cut  to  fit  the  subsurface  and  the  finished  grade  of  the  concrete, 
and  shall  be  withdrawn  from  the  concrete  one  hour  after  placing 
same,  and  the  space  left  open  thereby  shall  be  filled  with  hot 
pitch  or  some  other  approved  bituminous  filler. 

Protection  of  Work.  After  the  concrete  shall  have  been 
placed  it  shall  be.  protected  from  traffic  for  at  least  1  week.  While 
constructing  one-half  of  the  roadway,  traffic  may  be  permitted 
on  the  other  half. 

Connecting  up  Work.  After  one-half  of  the  roadway  has 
been  completed,  the  remaining  half  shall  be  laid  in  the  same 
manner  as  the  first  half,  making  expansion  joints  continuous 
with  the  first  half. 

No  roller  shall  be  permitted  on  the  concrete  roadway  until  2 
weeks  after  the  whole  has  been  completed. 

Other  Materials.  Bids  will  also  be  received  for  other  pro- 
prietary methods  of  making  a  concrete  road.  If  another  proprie- 
tary method  is  used  it  will  be  placed  and  the  work  done  in 


321 


102         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

general  under  the  specifications  of  the  manufacturer  in  conjunc- 
tion with  the  regular  specifications  of  the  Department. 

Grading,  drainage,  and  telford  or  macadam  foundations,  and 
all  other  things  to  be  done  in  the  reconstruction  must  be  done 
under  the  general  specifications  of  the  State  Highway  Department 
for  road  reconstruction. 

PAVEMENTS  AND  CURBING 
GENERAL 

Removal  or  Adjustment  of  Fixtures.  The  adjustment  or  re- 
setting of  any  manholes,  fire  hydrants,  lamp  posts,  gas  stops, 
telegraph  or  electric  light  poles,  or  other  fixtures  shall  be  con- 
sidered as  an  appurtenant  to  the  work  of  paving  and  repaving; 
and  shall  be  included  as  such  in  the  work  to  be  done  by  the  Con- 
tractor for  the  prices  bid  for  paving  and  repaving.  Such  adjust- 
ment or  resetting  shall  be  done  by  the  companies  owning  them, 
or,  if  the  property  of  the  City,  by  the  proper  municipal  Depart- 
ment; but,  in  either  case,  it  shall  be  done  at  the  expense  of  the 
Contractor. 

Granite  Blocks  on  Gravel  Base.  For  granite  block  paving 
on  gravel  base  in  driveways  or  gutters,  the  filling  shall  be  thor- 
oughly compacted  to  a  subgrade  10  inches  below  the  finished 
grade,  and  a  layer  of  approved  paving  gravel  spread  on  it  to  a 
least  thickness  of  4  inches.  The  blocks  shall  be  placed  vertically 
on  edge  in  straight  rows  at  right  angles  to  the  curb  line,  in  close 
contact,  breaking  joints;  and  they  shall  be  thoroughly  rammed 
three  times  with  a  rammer  weighing  not  less  than  55  pounds ;  and 
the  finished  surface  shall  conform  exactly  to  the  required  grade. 
While  the  blocks  are  being  rammed,  approved  paving  gravel  or 
sand  shall  be  swept  into  the  joints  until  they  are  completely 
filled.  All  irregular  or  uneven  surfaces  shall  be  taken  up  and 
reset  and  re-rammed  to  the  proper  grade. 

Repaving,  Resetting  Curb,  etc.  In  repaving  and  in  the  reset- 
ting of  curbs  and  crossing  stones,  the  foundations  shall  be  pre- 
pared and  all  the  work  shall  be  done  as  required  for  new  paving 
of  the  same  kind.  Old  materials  that  may  be  suitable  for  replac- 
ing may  be  used  only  after  satisfactory  preparation  by  special 
permission,  and  as  directed. 

Revision  of  Old  Paving.  Any  revision  of  old  paving,  gutter 
ways,  crossings,  or  curbs,  where  the  new  work  joins  the  old  work, 
shall  be  made  as  directed,  and  paid  for  as  provided  in  the  proposal. 

Cleaning.  Upon  the  completion  of  any  pavements  the  Con- 
tractor shall  clean  them  promptly  of  all  refuse  or  surplus 
materials. 


322 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         103 

Gutters.  The  finished  grade  for  the  gutters  shall  generally 
be  5  inches  below  the  top  of  the  curb,  except  where  given  differ- 
ently on  the  drawings,  or  where  a  change  is  directed  by  the 
Engineer,  to  insure  proper  surface  drainage. 

Crowning  or  Rise.  The  crowning  or  rise  of  the  finished  pave- 
ments in  the  driveways  shall  be  uniform  from  the  gutters  toward 
the  center  of  the  street ;  and  at  the  rate  of  2£  per  cent  for  granite 
block  or  vitrified-clay  brick  or  block  pavement,  and  2^  per  cent 
for  asphalt  pavement;  except  at  intersections,  or  where  the  sur- 
face drainage  demands  a  different  crown,  or  as  may  be  directed 
by  the  Engineer.  Gutter  and  crown  stakes  must  be  set  every  50 
feet.  The  rise  of  the  sidewalk  pavement  shall  be  as  directed  by 
the  Engineer. 

DRIVEWAY   PAVEMENTS   OF   VITRIFIED=CLAY   BRICKS   OR 
BLOCKS,  GRANITE  BLOCKS,  AND  ASPHALT 

Bed.  The  bed  for  driveway  paving  shall  be  graded  from 
curb  to  curb,  and  thoroughly  compacted  by  rolling  with  a  heavy 
steam  roller,  weighing  not  less  than  5  gross  tons,  until  the  surface 
shall  be  accurate  to  subgrade  and  parallel  to  it.  The  subgrade 
shall  be  below  the  intended  finished  grade,  as  follows:  for  vitri- 
fied-clay brick  or  block  pavement,  11  inches;  for  granite  block 
pavement,  15  inches ;  for  asphalt  pavement,  9  inches.  All  soft 
and  spongy  places  shall  be  excavated  and  refilled  with  gravel 
or  broken  stone  before  rolling.  The  use  of  a  horse  roller  will  be 
allowed  where,  in  the  judgment  of  the  Engineer,  the  use  of  a 
steam  road  roller  may  be  impracticable  on  account  of  steep  grades 
or  other  local  conditions. 

Concrete  Foundation.  Mixing  and  Laying.  Upon  the  bed 
shall  be  laid  a  layer  6  inches  thick  of  Portland  cement  concrete 
in  which  is  used  stone  crushed  to  pass  a  1^-inch  ring.  The  con- 
crete shall  be  rammed  with  25-pound  rammers  until  free  mortar 
appears  on  the.  surface,  which  surface  shall  be  parallel  to  and 
below  the  top  of  the  finished  pavement,  as  follows :  5  inches  for 
vitrified-clay  brick  or  block  pavement;  9  inches  for  granite 
block  pavement;  and  3  inches  for  asphalt  pavement. 

Carting  and  Wheeling.  No  carting  or  wheeling  will  be 
allowed  on  the  concrete  until  covered  by  paving. 

Tests.  The  concrete  foundation  shall  be  capable  of  sustain- 
ing such  test  as  the  Engineer  shall  deem  necessary. 

Kept  Clean  and  in  Advance  of  Paving.  In  paving,  the  Con- 
tractor must  keep  the  concrete  base  to  the  proper  grade  or  slope 
at  least  100  feet  in  advance  of  his  paving,  and  the  latter  must 
be  laid  in  sections  the  full  width  of  the  street.  The  concrete 


104         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

surface  shall  be  thoroughly  cleaned  of  gravel,  rubbish,  or  cover- 
ing of  any  description,  before  any  mortar  or  sand  is  placed  in 
which  the  bricks  or  blocks  are  to  be  bedded. 

VITRIFIED-CLAY  BRICK  OR  BLOCK  PAVING 

Samples  for  Testing.  When  paving  with  vitrified-clay  bricks 
or  blocks  is  required,  the  Contractor  shall  submit  sample  bricks 
or  blocks,  and  afford  every  facility  for  inspection  and  testing  at 
least  10  days  before  desiring  to  use  them.  The  failure  of  any 
shipment  on  any  work  to  meet  the  requirements  may  prohibit  the 
further  use  of  the  same  manufacture  on  that  work. 

Size  and  Quality.  The  bricks  or  blocks  must  be  vitrified  fire- 
clay, re-pressed,  and  especially  burned  for  street  paving,  not  less 
than  9  inches  long,  4  inches  wide,  and  3  inches  thick.  They  shall 
be  tough,  homogeneous,  compact  in  structure,  and  burned  to  a 
uniform  consistency.  They  shall  be  free  from  laminations  or 
"fire  cracks"  or  "checks"  of  more  than  superficial  extent;  shall 
be  free  from  nodules  of  lime  or  magnesia  or  other  soluble  matter ; 
and  shall  show  no  signs  of  cracking  after  48  hours'  immersion 
in  water  maintained  at  normal  temperature  (60-70°  F.). 

Variations  in  Size.  All  bricks  or  blocks  will  be  allowed  a 
proper  shrinkage,  but  they  must  not  vary  more  than  3  per  cent 
from  the  accepted  samples.  All  bricks  or  blocks  so  distorted  in 
burning  as  to  lie  unevenly  in  the  pavement  will  be  rejected. 

Shape.  The  bricks  or  blocks  must  have  two  or  more  ribs  or 
projections  upon  one  of  the  vertical  sides,  extending  from  top  to 
bottom;  on  the  opposite  vertical  side  of  the  brick  or  block,  a 
groove  or  channel  extending  longitudinally  from  the  end  of  the 
brick  or  block,  and  connecting  with  a  like  transverse  groove  ex- 
tending across  each  end;  thus  serving  by  contact  with  the  flat 
side  of  an  adjoining  brick  or  block,  to  secure  a  separation,  in 
order  that  cementing  material,  flowing  into  the  grooves,  may 
effect  a  practical  encircling  of  each  brick  or  block,  thus  keying 
or  locking  together  the  entire  pavement. 

Testing.  Samples  of  bricks  or  blocks  for  testing  will  be  se- 
lected at  random  from  actual  shipments  delivered  on  the  work, 
and  must  yield  the  following  results: 

Five  of  the  bricks  or  blocks  so  sampled  will  be  tested  transversely  and  shall 
develop  an  average  strength  sufficient  to  sustain  a  load  of  3000  pounds  per 
inch  of  width.  The  bricks  or  blocks  in  this  test  shall  be  supported  edgewise, 
on  rounded  knife  edges  placed  6  inches  apart;  the  breaking  load  being  applied 
centrally.  Five  bricks  or  blocks  shall  be  placed  in  a  standard  polygonal  nim- 
bler (20  inches  wide,  30  inches  in  diameter),  together  with  10  cast-iron  bricks 
(weighing  6  pounds  each),  having  rounded  edges.  This  nimbler  will  be  revolved 


324 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         105 

2000  times  at  the  rate  of  35  revolutions  per  minute,  and  the  brick  must  not 
show  an  average  loss  of  more  than  18  per  cent.  The  bricks  or  blocks  coming 
from  the  rumbler  shall  be  dried  for  24  hours  at  a  temperature  of  not  less  than 
212°  F. ;  and  after  48  hours'  immersion  in  water,  maintained  at  a  normal 
temperature,  shall  not  show  an  absorption  of  more  than  4  per  cent. 

Laying.  The  bricks  or  blocks  must  be  set  vertically  on  edge 
in  close  contact  with  each  other,  in  straight  rows  across  the  street, 
excepting  at  intersections,  which  shall  be  paved  at  an  angle  of 
45  degrees  to  the  lines  of  the  intersecting  roadways,  and  those 
in  adjoining  rows  so  set  as  to  break  joints  regularly.  No  bats 
or  broken  bricks  or  blocks  shall  be  used  except  at  curbs,  or 
adjoining  passenger  railway  rails,  where  half  bricks  or  blocks 
must  be  used  to  break  joints.  The  bricks  or  blocks  shall  be 
bedded  in  a  layer  of  Portland  cement  mortar  1  inch  in  thickness, 
freshly  mixed,  and  laid  upon  the  concrete  foundation  as  the 
placing  of  the  bricks  or  blocks  progresses.  They  shall  be  true  to 
the  required  finished  surface  when  completed,  and  shall  be  settled 
in  place,  after  depositing,  by  placing  a  plank  upon  their  tops 
and  ramming  the  plank  as  required,  with  wooden  rammers,  before 
the  mortar  bedding  has  time  to  set  and  as  the  work  progresses. 

Grouting.  After  the  bricks  or  blocks  are  laid,  they  shall  be 
grouted  with  Portland  cement  grouting,  consisting  of  one  part 
cement  to  one  part  clean  bar  sand,  mixed  with  water  to  such 
consistency  that  it  will  readily  permeate  the  joints,  filling  all 
joints  flush  with  the  surface. 

Car  Tracks.  "When  car  tracks  cross  the  deck  of  a  bridge,  a 
line  of  fitted  granite  blocks  or  slag  blocks  shall  be  laid  on  each 
side  of  each  rail,  placed  longitudinally  or  as  stretchers.  The 
blocks  so  used  shall  be  made  especially  for  street  paving,  shall 
have  beveled  edges  on  top,  and  be  of  size  and  quality  to  be  ap- 
proved by  the  Engineer  upon  the  submission  of  samples  properly 
labeled,  the  accepted  sample  to  be  the  standard.  All  voids  under 
the  heads  and  side  bearing  flanges,  between  the  webs  of  the  rails 
and  the  paving  blocks,  shall  be  filled  with  special  molded  bricks, 
thoroughly  grouted  with  Portland  cement  grout  to  fill  all  crevices. 

GRANITE  BLOCK   PAVING  ON  CONCRETE  BASE 

Granite  Blocks.  Granite  blocks  shall  be  fitted  blocks  of  ap- 
proved Eastern  granite,  with  square  heads  and  bottoms,  and  in 
sizes  from  6  to  6£  inches  in  depth,  3£  inches  in  width,  8  to  12 
inches  in  length ;  4  inches  in  width,  8  to  12  inches  in  length ;  and 
4£  inches  in  width,  8  to  12  inches  in  length ;  to  be  sorted  at  the 
quarries  at  the  above  sizes,  kept  separate,  and  delivered  and  set 


325 


106         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

separately;  all  the  faces  of  the  blocks  shall  be  non-warped  and 
parallel;  free  from  bunches,  depressions,  and  inequalities  exceed- 
ing one-fourth  inch;  and  no  stones  shall  measure  less  than  the 
above-named  lowest  figures. 

Laying.  Upon  the  concrete  foundation  for  granite  block 
paving  shall  be  placed  a  layer  3  inches  thick  of  sharp,  approved, 
coarse  New  Jersey  paving  sand,  upon  which  the  blocks  shall  be 
bedded.  Granite  blocks  shall  be  properly  assorted  or  gaged,  those 
of  the  same  width  and  depth  to  be  placed  in  consecutive  rows ;  blocks 
differing  in  width  more  than  one-fourth  inch  will  not  be  allowed 
in  the  same  row.  They  shall  be  placed  vertically  on  edge  in  close 
contact  with  each  other  across  the  street;  in  straight  rows  and 
at  right  angles  to  the  curbing,  except  at  intersections,  where 
they  shall  be  placed  at  an  angle  of  45  degrees  to  the  lines  of  the 
intersecting  roadways.  Blocks  in  adjoining  rows  shall  be  set  to 
break  joints  by  a  space  not  less  than  4  inches,  and  when  thor- 
oughly rammed  they  shall  be  brought  to  the  exact  grade.  Joints 
shall  not  be  more  than  one-half  inch  in  thickness.  At  all  times  dur- 
ing the  progress  of  the  work  100  lineal  feet  of  the  paving  must  be 
laid  continually  in  advance  of  filling  and  ramming,  to  permit  the 
proper  inspection  of  the  blocks  and  the  work.  The  pavement 
must  be  laid  so  that  the  blocks  shall  be  uniform  in  width  in  sec- 
tions across  the  full  width  of  the  street. 

Ramming — Filling  Joints.  The  pavements  shall  be  rammed 
three  times  with  55-pound  rammers,  until  no  further  settling 
occurs  under  the  ramming.  While  being  rammed  the  joints  shall 
be  kept  well  filled  with  dry  pebbles.  Any  blocks  that  do  not 
conform  to  the  exact  grade  shall  be  reset  and  re-rammed.  The 
pebbles  for  filling  joints  shall  be  quartz,  hard,  clean,  well  washed, 
and  not  easily  crushed,  one-eighth  to  one-fourth  inch  in  diameter, 
entirely  free  from  dust,  dirt,  or  foreign  material,  and  thoroughly 
dry  when  delivered.  Immediately  after  the  final  ramming  the  peb- 
bles shall  be  swept  out  to  a  depth  of  1  inch  from  the  top  of  the 
pavement,  and  the  joints  filled  with  hot  paving  pitch,  applied  in 
liquid  form.  The  pitch  must  be  prepared  for  paving  purposes,  so 
that  it  can  be  easily  applied  in  the  liquid  state  when  artificially 
heated,  and  used  to  fill  the  joints  thoroughly  and  not  spread  over 
the  face  of  the  paving.  While  the  paving  pitch  is  still  hot,  dry  sand 
.shall  be  spread  very  thinly  over  the  entire  surface  of  the  pavement. 

Dry  Material.  If  the  weather  be  damp  while  the  paving  is 
being  done,  or  if  the  pebbles  become  wet,  they  shall  be  artificially 
heated  and  kept  hot  until  they  are  flooded  with  the  paving  pitch. 

Tracks.  When  passenger  railway  tracks  are  to  be  laid,  one 
line  of  granite  blocks  shall  be  laid  longitudinally,  or  as  stretchers, 
along  each  side  of  each  rail.  All  voids  under  the  heads  and 


326 


CIVIL  SPECIFICATIONS  AND  CONTRACTS          107 

treads  of  the  rails  shall  be  filled  with  specially  molded  bricks,  and 
then  thoroughly  grouted  to  fill  all  voids. 

TELFORD  PAVING 

Roadbed.  The  bed  shall  be  thoroughly  compacted  by  rolling 
with  a  steam  roller  weighing  not  less  than  5  gross  tons,  to  be 
parallel  to  and  12  inches  below  the  finished  surface,  as  given  by 
the  District  Surveyor. 

Sub-Stone  Pavement.  Upon  the  bed  shall  be  placed  a  sub- 
stone  pavement  not  less  than  8  inches  deep,  consisting  of  hard 
approved  stones,  not  less  than  12  inches  in  their  longest  diameter, 
placed  vertically  on  edge,  in  rows  square  across  the  driveway, 
so  as  to  break  joints.  Projecting  points  in  the  subpavement 
shall  be  broken  off  with  knapping  hammers,  after  which  more 
stone  shall  be  broken  by  hand  on  top  and  wedged  between  the 
pavement  stones  until  all  cavities  are  filled. 

Surface  Layers.  A  layer  of  clean  loam,  not  less  than  1  inch 
thick,  shall  be  deposited  on  top  of  the  sub-stone  pavement.  Suffi- 
cient crushed  stone,  crushed  to  pass  a  1^-inch  ring,  of  hard  trap 
rock,  free  from  dirt,  shall  be  deposited  on  the  surface,  and  rolled 
with  the  steam  roller  previously  specified,  so  that  there  shall  not 
be  less  than  4  inches  of  the  crushed  stone  on  top  of  the  founda- 
tion stone.  After  rolling  the  crushed  stone,  a  covering  of  fine 
stone,  breaker  scale,  or  screenings  of  trap  rock  shall  be  evenly 
spread,  kept  wet,  and  rolled  continuously,  until  the  whole  shall 
be  a  compact  mass,  2  inches  above  the  finished  surface  as  fixed 
by  the  Engineer. 

CURBING 

Materials.  Curbing  shall  be  furnished  where  required  by  the 
drawings,  and  shall  be  either  of  steel  protected  granolithic  or  of 
first  quality  granite.  Granite  shall  be  neither  laminated  nor 
stratified,  shall  be.  hammer-dressed  on  the  face  at  least  12  inches 
deep  over  all  of  the  top  surface,  and  3  inches  deep  on  the  back  to 
receive  the  sidewalk  pavement. 

All  joints  shall  be  close  joints,  the  full  depth  and  width  of 
the  stones. 

Dimensions.  Curbing  shall  be  either  6  or  8  inches  wide  on 
top,  as  specified;  8-inch  curbing  shall  be  24  inches  in  depth  and 
10  inches  in  width  at  the  base ;  6-inch  curbing  shall  be  22  inches 
in  depth  and  8  inches  in  width  at  the  base. 

Straight  curbing  shall  not  be  less  than  6  feet  in  length,  and 
curved  curbing  shall  not  be  less  than  5  feet  in  length,  and  no 
closure  shall  be  less  than  4  feet  in  length.  Where  curved  curbs 


108         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

are  required  in  excess  of  8  feet  in  length  the  stone  may  be  in 
two  pieces,  either  of  which  may  be  less  than  5  feet  in  length,  but 
the  joint  must  be  in  the  center. 

Foundations.  Curbs  shall  be  set  upon  a  solid  foundation  pre- 
pared for  them,  of  coarse  gravel  or  spalls,  backed  with  gravel, 
all  solidly  rammed. 

The  foundation  of  the  sidewalk  paving  back  of  the  curbs  shall 
be  thoroughly  compacted  by  ramming,  before  the  sidewalk  paving 
is  laid. 

Curbstones  set  adjacent  to  inlets  shall  be  square  on  their  ends 
the  full  depth  of  the  stones,  and  the  castings  for  inlet  covers, 
stop  boxes,  or  other  municipal  or  other  castings,  shall  be  cut  into 
the  curbing,  flush  with  the  top  of  the  curb. 

Curved  Curbs.  When  curved  curbs  are  placed,  the  Contractor 
shall  extend  the  crossing  stones  to  conform  to  the  radius  curbs. 
All  curved  curbing  shall  be  cut  exactly  true  to  the  radius  ordered, 
and  set  to  the  lines  and  grades  to  be  obtained  from  the  Engineer. 

Joints.  All  joints  of  curbing  shall  be  thoroughly  back  filled, 
and  made  water-tight  from  the  base  to  the  top  of  the  curbing  with 
Portland  cement  mortar,  made  of  one  part  Portland  cement  and 
two  parts  clean  sand,  thoroughly  mixed  into  a  stiff  mortar. 

All  curbs  moved  or  displaced,  or  any  sidewalks  injured  or 
destroyed  by  the  Contractor,  or  those  employed  by  him,  either 
while  grading  for  the  paving  or  in  the  handling,  placing,  or 
removal  of  materials,  supplies,  etc.,  must  be  reset,  replaced,  or 
repaved  in  proper  manner  by  the  Contractor  at  his  expense. 

GRANITE  BLQCK  PAVING  ON  SAND  BASE 

Preparation  of  Foundation.  The  spaces  to  be  paved  between 
the  lines  shown  on  the  plans  shall  be  graded  and  thoroughly 
compacted  by  rolling  with  a  heavy  steam  roller,  weighing  not 
less  than  12  gross  tons,  until  the  surface  shall  be  brought  accu- 
rately to  subgrade  and  parallel  with  and  10  inches  below  the 
finished  surface.  All  soft  places  shall  be  dug  out  and  filled  with 
paving  sand.  The  subgrade  must  be  compacted  to  a  solid  foun- 
dation, and  must  be  approved  before  the  block  paving  is  laid. 
Sharp,  approved,  coarse  paving  sand  shall  be  spread  upon  the 
foundation,  to  a  depth  of  at  least  4  inches,  upon  which  the  blocks 
shall  be  bedded. 

Granite  Blocks.  Granite  blocks  shall  be  fitted  blocks  of  ap- 
proved granite  3^  to  4  inches  wide,  6  to  6^  inches  deep,  8  to  12 
inches  long,  with  square  heads,  smooth  faces,  and  rectangular 
edges.  They  shall  be  subject  to  inspection  and  shall  be  gaged 
and  sorted  by  men  furnished  by  the  Contractor;  any  blocks  re- 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         109 

jected  shall  be  immediately  removed  from  the  vicinity  of  the 
work.  Those  of  the  same  width  and  depth  shall  be  placed  in  con- 
secutive rows,  and  blocks  differing  in  width  more  than  one-fourth 
inch  shall  not  be  allowed  in  the  same  row.  They  shall  be  placed  ver- 
tically on  edge  in  close  contact  with  each  other  across  the  space 
to  be  paved ;  in  straight  rows  and  at  right  angles  to  the  curbing, 
except  at  intersections,  where  they  shall  be  placed  at  an  angle 
of  45  degrees  to  the  lines  of  the  intersecting  roadways.  Blocks 
in  the  adjoining  rows  shall  be  set  to  break  joints  by  a  space  of 
not  less  than  4  inches,  and  when  thoroughly  rammed  they  shall 
be  brought  to  the  exact  grade.  Joints  shall  not  be  more  than  one- 
half  inch  in  thickness.  At  all  times  during  the  progress  of  the  wrork, 
about  100  lineal  feet  of  the  paving  shall  be  laid  continuously  in 
advance  of  filling  and  ramming,  to  permit  the  proper  inspection 
of  the  work.  The  pavement  shall  be  laid  so  that  the  blocks  shall 
be  uniform  in  width  in  sections  across  the  full  width  of  the  space 
being  paved. 

Filling  Joints.  The  joints  between  the  blocks  shall  then  at 
once  be  filled  with  paving  sand  and  shall  be  rammed  three  times 
\vith  55-pound  rammers  until  no  further  settling  occurs  under 
the  ramming.  "While  being  rammed  the  joints  should  be  kept 
well  filled  with  paving  sand.  Any  blocks  that  do  not  conform 
to  the  exact  grade  shall  be  reset  and  rammed. 

Payment.  Payment  will  be  made  for  this  paving  at  the  price 
per  square  yard  given  in  the  proposal,  which  price  shall  include 
everything  except  such  excavation  as  may  be  necessary  for  pre- 
paring the  subgrade. 

ASPHALT  PAVING 

Samples  to  be  Submitted.  If  asphalt  pavement  is  to  be  laid, 
the  Contractor  shall  submit  to  the  Commissioner  of  Highways 
samples  of  the  materials  he  intends  to  use,  together  with  certifi- 
cates and  statements  as  follows : 

(1)  Specimens  of  asphalt  and  asphaltum,  with  a  certificate 
stating  where  the  specimens  were  mined. 

(2)  A  specimen  of  the  asphaltic  cement,  with  a  statement  of 
the  elements  of  the  bituminous  cements  used  in  the  composition 
of  the  paving  surface. 

(3)  Specimens  of  sand  intended  to  be  used. 

(4)  Specimens  of  pulverized  carbonate  of  lime,  granite,  or 
quartz  intended  to  be  used. 

(5)  A  certificate,  if  the  material  proposed  to  be  used  has  not 

heretofore  been  used  in  the  City  of. ,  showing  some 

other  locality  where  pavement  of  such  material  has  been  laid, 
its  area,  date  of  acceptance,  which  must  have  been  at  least  2 


110         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

years  previous  to  the  issuance  of  the  certificate,  and  showing 
that  said  pavement  has  worn  well  and  satisfactorily;  all  to  be 
signed  and  acknowledged  by  the  chief  municipal  officer  having 
charge  of  said  work  in  the  city  or  cities  where  such  pavement 
has  been  laid. 

Such  specimens,  certificates,  and  statements  must  be,  in  the 
judgment  of  the  Engineer,  equal  in  all  respects  to  similar  con- 
ditions exacted  by  the  Department  of  Highways  for  other  asphalt 
pavement  in  the  City  of 

Subgrade  for  Asphalt.  The  backfilling  on  the  top  of  the 
trench  shall  be  of  clean  gravel  or  sand,  or  other  wholesome  earth, 
free  from  all  spongy  or  vegetable  material ;  and  thoroughly  rolled 
with  a  roller  weighing  not  less  than  10  tons,  so  that  the  top  of 
the  filling  is  parallel  to  the  crown  of  the  street  and  9  inches 
below  it;  except  beneath  the  stone  block  pavement  adjoining 
rails,  manhole  heads,  and  stopcock  boxes,  where  the  depth  below 
the  finished  grade  shall  be  13£  inches.  When  the  roller  cannot 
reach  every  portion  of  the  roadbed,  the  bottom  shall  be  rolled 
by  a  small  roller,  or  tamped,  as  directed  by  the  Engineer,  and 
water  shall  be  sprinkled  on  such  bottom  when  required.  Upon 
the  foundation  thus  prepared,  there  shall  be  laid  a  bed  of  hy- 
draulic cement  concrete  6  inches  in  thickness,  and  made  as 
f  ollows : 

Cement.  All  cement  must  be  of  the  best  quality,  of  fresh- 
ground  best  American  Portland  cement,  and  shall  be  tested  and 
approved  by  the  Engineer  before  being  used. 

Portland  Cement  Concrete.  Concrete  shall  be  composed  of  1 
part  of  cement,  3  parts  of  clean  sharp  sand,  and  7  parts  of 
broken  stone;  or  1  part  of  cement,  3  parts  of  clean  sharp  sand, 
4  parts  of  broken  stone,  and  3  parts  of  pebbles  by  measure. 

Mixing.  The  cement  and  sand  shall  be  mixed  dry ;  the  broken 
stone  having  been  first  wetted  shall  then  be  added  and  the  mass 
turned  over,  with  the  addition  of  the  necessary  water,  and  worked 
until  the  broken  stone  is  completely  incorporated. 

Pebbles.  The  pebbles  shall  be  hard,  clean,  free  from  sand, 
screened  and  washed,  and  of  a  size  that  has  passed  a  sieve  of 
1^-inch  mesh  and  rejected  by  a  three-fourths-inch  mesh. 

Broken  Stone.  The  broken  stone  shall  be  solid  trap,  limestone, 
or  granite,  free  from  dust  or  dirt,  and  of  a  graded  size  not  larger 
in  any  dimension  than  will  pass  through  a  2-inch  ring;  and  it 
shall  be  crushed  and  screened  before  being  brought  upon  the 
work ;  and  no  crushing  shall  be  done  on  the  work. 

Concrete  to  be  Rammed.  The  concrete  shall  be  placed  in 
proper  position  and  there  rammed  with  wooden  rammers  until 
thoroughly  compacted;  the  surface  shall  be  3  inches  below 


330 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         111 

the  grade  of  the  top  of  the  finished  pavement  and  exactly  parallel 
thereto. 

The  concrete  foundation  shall  be  capable  of  sustaining  such 
test  as  the  Engineer  shall  deem  necessary. 

No  carting  or  wheeling  shall  be  allowed  on  the  concrete  until 
it  is  sufficiently  set,  and  then  only  on  planks  laid  down  for  the 
purpose. 

Mixing  Concrete.  The  whole  operation  of  mixing  and  laying 
each  batch,  which  shall  not  contain  more  than  1  barrel  of  cement, 
must  be  performed  as  expeditiously  as  possible  by  the  employ- 
ment of  a  sufficient  number  of  skilled  men  and,  if  necessary,  must 
be  protected  from  the  action  of  the  sun  and  wind  until  set.  No 
concrete  will  be  allowed  to  be  used  which  has  been  mixed  more 
than  30  minutes. 

Bituminous  Binder.  Composition.  Upon  this  concrete  foun- 
dation must  be  laid  a  fine  bituminous  concrete  or  binder,  to  be 
composed  of  clean  broken  stone  not  exceeding  1^  inches  in  their 
largest  dimensions,  thoroughly  screened,  and  either  coal-tar  re- 
siduum, commonly  known  as  No.  4  paving  composition,  or  the 
same  bitumen  used  in  the  body  of  the  pavement. 

Stone  to  be  Heated.  The  stone  must  be  heated  by  being  passed 
through  revolving  heaters  and  must  be  thoroughly  mixed  by 
machinery,  with  the  paving  composition  in  the  proportion  of  1 
gallon  of  paving  composition  to  1  cubic  foot  of  stone. 

Laying  of  Binder.  This  binder  must  be  hauled  to  the  work 
and  spread  with  hot  iron  rakes  in  all  holes  or  inequalities  and 
depressions  below  the  true  grade  of  the  pavements,  to  such  thick- 
ness that,  after  being  thoroughly  compacted  by  tamping  and 
hand  rolling,  the  surface  shall  have  a  uniform  grade  and  cross 
section,  and  the  thickness  of  the  binder  at  any  point  shall  be  not 
less  than  three-fourths  inch.  No  binder  shall  be  laid  during  a  rain, 
nor  shall  any  binder  be  laid  that  is  too  cold  to  be  manipulated 
easily ;  overheated  binder  shall  be  removed  entirely  from  the  work. 

The  upper  surface  shall  be  exactly  parallel  with  the  surface 
of  the  pavement  to  be  laid. 

Wearing1  Surface.  Upon  this  foundation  must  be  laid  the 
wearing  surface,  or  paving  proper,  the  basis  of  which  must  be 
pure  asphaltum,  unmixed  with  any  of  the  products  of  coal  tar. 

The  wearing  surface  will  be  composed  of : 

(1)  Refined  asphaltum;  (2)  heavy  petroleum  oil;  (3)  fine 
sand,  containing  not  more  than  1  per  cent  of  hydrosilicate  of 
alumina ;  (4)  fine  powder  of  carbonate  of  lime,  granite,  or  quartz. 

Heavy  Petroleum  Oil  The  heavy  petroleum  oil  must  be  freed 
from  all  impurities  and  brought  to  a  specific  gravity  of  from 
18°  to  22°  Baume,  and  a  fire  test  of  250°  F.,  or,  if  the  formula 


331 


112          CIVIL  SPECIFICATIONS  AND  CONTRACTS 

of  the  Contractor  requires  it,  the  powdered  carbonate  of  lime 
may  be  omitted,  and  the  heavy  petroleum  oil  may  be  replaced 
by  sufficiently  fluid  natural  bitumen. 

Asphaltum.  The  asphaltum  used  must  be  equal  in  quality  to 
that  mined  from  the  Pitch  Lake  on  the  Island  of  Trinidad,  or 
from  the  Alcatraz  mine,  Santa  Barbara  County,  California,  and 
must  be  specially  refined  and  brought  to  a  uniform  standard  of 
purity  and  gravity,  of  a  quality  to  be  approved  by  the  Engineer. 

Asphaltic  Cement.  From  these  two  hydrocarbons  shall  be 
manufactured  an  asphaltic  cement  which  shall  have  a  fire  test 
of  250°  F.,  and,  at  a  temperature  of  60°  F.,  shall  have  a  specific 
gravity  of  1.19,  said  cement  to  be  composed  of  100  parts  of  pure 
asphalt,  and  from  15  to  20  parts  of  heavy  petroleum  oil. 

Pavement  Mixture.  The  asphaltic  cement  being  made  in  the 
manner  above  described,  the  pavement  mixture  must  be  formed 
of  the  following  materials,  and  in  the  proportions  stated : 

Asphaltic  cement From  12  to  15 

Sand    From  83  to  70 

Pulverized  carbonate  of  lime,  gran- 
ite,  or  quartz From     5  to  15 

Sand.  The  sand  shall  be  of  such  size  that  none  of  it  shall 
pass  a  No.  80  screen,  and  that  the  whole  of  it  shall  pass  a  No.  10 
screen. 

Powdered  Stone.  The  powdered  carbonate  of  lime,  granite,  ot 
quartz  shall  be  of  such  a  degree  of  fineness  that  from  5  to  15  per 
cent  by  weight  of  the  entire  mixture  for  the  pavement  shall 
be  an  impalpable  powder  of  limestone,  and  the  whole  of  it  shall 
pass  a  No.  26  screen. 

How  Mixed.  The  sand  and  asphaltic  cement  are  to  be  heated 
separately  to  about  300°  F.  The  pulverized  carbonate  of  lime, 
granite,  or  quartz,  while  cold,  shall  be  mixed  with  the  hot  sand 
in  the  required  proportions,  and  then  mixed  in  a  suitable  apparatus 
with  the  asphaltic  cement  at  the  required  temperature,  and  in  the 
proportions  which  will  effect  a  perfect  mixture. 

Laying  of  Pavement  Mixture.  The  pavement  mixture  prepared 
in  the  manner  thus  indicated  must  be  brought  to  the  ground  in 
carts,  at  a  temperature  of  about  250°  F.  and,  if  the  temperature 
of  the  air  is  less  than  50°  F.,  iron  carts,  with  heating  appara- 
tus, shall  be  used  in  order  to  maintain  the  proper  temperature 
of  the  mixture;  it  shall  then  be  carefully  spread  by  means  of 
hot  iron  rakes  in  such  manner  as  to  give  a  uniform  and  regular 
grade.  The  surface  shall  be  compressed  by  hand  rollers,  after 
which  a  small  amount  of  hydraulic  cement  shall  be  swept  over  it, 
and  it  shall  then  be  thoroughly  compressed  by  a  steam  roller 


332 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         113 

weighing  not  less  than  250  pounds  to  the  inch  run,  the  rolling  to 
be  continued  for  not  less  than  5  hours  for  every  1000  square 
yards  of  surface.  After  having  received  its  ultimate  compres- 
sion, the  pavement  must  have  a  thickness  of  not  less  than  2  inches. 

Glitters.  The  gutters  for  a  width  of  12  inches  next  the  curb 
must  be  coated  with  hot,  pure  asphalt,  and  smoothed  with  hot 
smoothing  irons  in  order  to  saturate  the  pavement,  to  a  depth  to 
be  directed  by  the  Engineer,  with  an  excess  of  asphalt. 

Rock  Asphalt.  If  rock  asphalt  be  used,  the  material  shall  be 
an  amorphous  limestone,  which  is  naturally,  thoroughly,  and  uni- 
formly impregnated  with  bitumen:  (1)  From  the  Sicilian  mines 
at  Ragusa  and  Verwohle,  equal  in  quality  and  composition  to 
that  mined  by  the  United  Limmer  and  Verwohle  Rock  Asphalte 
Company,  Limited.  (2)  From  the  Swiss  mines  at  Val  de  Travers, 
equal  in  quality  and  composition  to  that  mined  by  The  Neuchatel 
Asphalte  Company,  Limited.  Or  (3)  from  the  French  mines  at 
Seyssel  and  Mons,  and  the  Sicilian  mines  at  Ragusa,  equal  in 
quality  and  composition  to  that  mined  by  the  Compagnie  Generate 
des  Asphaltes  de  France,  Limited,  and  it  shall  be  prepared  and  laid 
as  follows: 

Preparation.  The  rock  shall  be  finely  crushed  and  pulverized ; 
the  powder  shall  then  be  passed  through  a  fine  sieve.  Nothing 
whatever  shall  be  added  to  or  taken  from  the  powder  obtained 
by  grinding  the  bituminous  rock.  The  powder  shall  contain  9 
to  12  per  cent  natural  bitumen ;  88  to  91  per  cent  pure  carbonate 
of  lime ;  and  must  be  free  from  quartz,  sulphates,  iron  pyrites,  or 
aluminum. 

Powder  to  be  Heated.  This  powder  shall  be  heated  in  a  suit- 
able apparatus  to  200°-250°  F.,  and  must  be  brought  to  the  ground 
at  such  temperature,  in  carts  made  for  the  purpose;  then  care- 
fully spread  on  the  binder  foundation  previously  prepared  to  such 
depth  that,  after  having  received  its  ultimate  compression,  it  will 
have  a  thickness  of  not  less  than  2  inches. 

Surface  to  be  Rolled.  The  surface  shall  be  rendered  perfectly 
even  by  rammers  and  smoothers,  and  shall  be  rolled  with  a  steam 
roller  weighing  not  less  than  250  pounds  to  the  inch  run,  the 
rolling  to  continue  for  not  less  than  5  hours  for  each  1000  square 
yards  of  surface  in  the  case  of  Trinidad  asphalt;  in  the  case  of 
rock  asphalt  pavement  the  ultimate  compression  may  be  by 
heated  pilons. 

Special  Permission  to  Lay  Rock  Asphalt.  Rock  asphalt  shall 
not  be  used  in  any  case  without  written  permission  from  the 
Commissioner  of  Highways. 

Space  Next  to  Rails,  Manholes,  etc.  On  each  side  of  the  rails 
of  the  car  tracks,  around  all  manholes  and  stopcock  boxes,  the 


333 


114         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Contractor,  when  required,  shall  lay  a  line  of  granite  or  syenite 
paving  blocks,  as  headers;  long  and  short  stones  alternating  and 
toothing  into  the  pavement,  laid  on  a  foundation  of  6  inches  of 
concrete,  which  must  extend  to  the  depth  of  the  crossties  and 
beneath  and  around  the  girders  and  stringers;  on  which  shall 
be  laid  a  bed  of  fresh  cement  mortar,  2  inches  in  thickness;  and 
on  the  mortar  so  laid  shall  be  laid  the  stone  blocks,  the  top  sur- 
face of  which  shall  conform  to  the  grade  of  the  pavement.  The 
joints  of  the  blocks  shall  be  filled  with  paving  cement,  as  here- 
inafter described. 

Space  within  Car  Tracks.  Whenever  the  space  within  car 
tracks  has  been  laid  with  granite  or  syenite  blocks,  the  said  space 
shall  be  repaved  with  said  blocks  or  said  asphalt,  according  to 
the  determination  of  the  Engineer. 

REFINED  ASPHALT 
Solid  Bitumen  Base 

Materials  and  Tests.  The  refined  asphalt  to  be  used  for  paving 
mixtures  herein  required  shall  be  derived  in  the  following 
manner : 

1.  By  heating  crude,  natural,  solid  asphalt,  requiring  refine- 
ment, to  a  temperature  of  not  over  450°  F.,  until  all  the  water 
has  been  driven  off.    Crude,  natural,  solid  asphalt  shall  be  con- 
strued to  mean  any  natural  mineral  bitumen,   either  pure   or 
mixed  with  foreign  matter,  from  which,  through  natural  causes 
in  the  process  of  time,  the  light  oils  have  been  driven  off  until  it 
has  a  consistency  harder  than  100  penetration  at  77°  F.    At  least 
98|  per  cent  of  the  contained  bitumen  in  the  refined  asphalt,  which 
is  soluble  in  cold  carbon  disulphide,  shall  be  soluble  in  cold  carbon 
tetrachloride.    In  no  case  shall  such  asphalt  be  prepared  at  the 
refinery  with  any  product  not  hereinafter  provided  for. 

2.  By  the  careful  distillation  of  asphaltie  petroleum  with 
continuous  agitation  until  the  resulting  bitumen  has  a  consistency 
not  harder  than  30  penetration  at  77°  F. 

(a)  All  shipments  of  material  shall  be  marked  with  a  lot 
number  and  penetration;  and  ten  samples,  taken  at  random 
from  each  lot,  shall  not  vary  more  than  15  per  cent  from  the 
average  penetration,  provided  no  part  of  any  shipment  shall 
be  below  30  penetration  at  77°  F. 

(b)  The   solid  bitumen   so   obtained   shall   be   soluble   in 
carbon  tetrachloride  to  the  extent  of  98^  per  cent. 

(c)  When  20  grams  of  the  material  are  heated  for  5  hours 
at  a  temperature  of  325°  F.  in  a  tin  box  2^  inches  in  diameter, 


334 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         115 

after  the  manner  officially  prescribed,  the  material  shall  not 
lose  over  5  per  cent  by  weight  nor  shall  the  penetration  at 
77°  F.  after  such  heating  be  less  than  one-half  of  the  original 
penetration. 

(d)  The  solid  bitumen  at  a  penetration  of  50  shall  have 
a  ductility  of  not  less  than  20  centimeters  at  77°  F.  If  the 
penetration  varies  from  50,  an  increase  of  at  least  2  centi- 
meters in  ductility  will  be  required  for  each  five  points  in  pene- 
tration above  50 ;  and  a  corresponding  allowance  will  be  made 
below  50  penetration.  This  test  shall  be  made  with  a  briquette 
of  cross  section  of  one  square  centimeter,  the  material  being 
elongated  at  the  rate  of  5  centimeters  per  minute.  (Dow 
molds). 

NOTE. — Combinations  of  asphaltic  bitumens  having  the  ductility  and  other 
characteristics  above  mentioned  are  admitted  under  Section  2. 

3.  Refined  asphalt  produced  by  combining  crude  natural 
asphalt  with  either  of  the  following: 

(a)  Residuums  obtained  by  the  distillation  of  petroleum 
oils  as  specified  under  fluxes. 

(b)  Asphalts  obtained  by  the  distillation  of  petroleum  oils 
as  specified. 

Use  of  Bitumen  Mixtures.  Fluxes.  In  the  use  of  these  mix- 
tures of  refined  asphalts  for  asphaltic  cements,  only  asphaltic 
or  semi-asphaltic  fluxes  shall  be  used,  except  in  those  cases  where 
the  solid  natural  asphalt  is  of  such  character  that  when  mixed 
with  paraffin  flux,  without  the  addition  of  any  other  material,  it 
will  produce  an  asphaltic  cement  complying  with  the  require- 
ments set  forth  under  that  head.  In  such  cases  any  of  the  fluxes 
elsewhere  specified  may  be  used. 

Inspection.  The  preparation  and  refining  of  all  asphalt  ad- 
mitted under  these  specifications  shall  be  subject  to  such  inspec- 
tion at  the  paving  plants  and  refineries  as  the  Engineer  may 
direct. 

Flux 

Material.  The  fluxing  material  may  be  a  paraffin,  a  semi- 
asphaltic,  or  an  asphaltic  residue  which  shall  be  tested  with  and 
found  suitable  to  the  asphalts  to  be  used. 

Tests.  Penetration.  The  residuums  must  have  a  penetration 
greater  than  350,  with  a  No.  2  needle  at  77°  F.  under  50  grams 
weight  for  1  second. 

Solubility.  All  residuums  shall  be  soluble  in  cold  carbon  tetra- 
chloride  to  the  extent  of  99  per  cent,  and  must  remain  soft  after 
heating  for  5  hours  at  400°  F. 


335 


116         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Miscellaneous,  (a)  The  paraffin  residuum  shall  have  a  specific 
gravity  of  from  0.92  to  0.94  at  77°  F.  It  shall  not  flash  below  350° 
F.  when  tested  in  the  New  York  State  Closed  Oil  Tester,  and  shall 
not  volatilize  more  than  5  per  cent  of  material  when  heated  5 
hours  at  325°  F.  in  a  tin  box  2£  inches  in  diameter,  as  officially 
prescribed.  The  residue  after  heating  shall  flow  at  77°  F.  and 
shall  be  homogeneous  and  shall  show  no  coarse  crystals. 

(b)  Semi-asphaltic  residuum  shall  have  the  same  general  char- 
acteristics as  paraffin  residuum  except  that  it  shall  have  a  spe- 
cific gravity  of  0.94  to  0.98  at  77°  F. 

Asphaltic  Cement 

Proportions  of  Asphalt  and  Flux.  The  asphaltic  cement  pre- 
pared from  materials  above  designated  shall  be  made  up  from 
the  refined  asphalt  or  asphalts,  and  the  flux,  where  flux  must  be 
used,  in  such  proportions  as  to  produce  an  asphaltic  cement  of  a 
suitable  degree  of  penetration.  The  proportion  of  the  refined 
asphalt,  comprising  the  cement,  shall  in  no  case  be  less  than  40 
per  cent  by  weight. 

When  the  weight  of  flux  in  the  asphaltic  cement  prepared 
from  solid  natural  asphalt  exceeds  25  per  cent  thereof,  asphaltic 
or  semi-asphaltic  flux  shall  be  used. 

Refined  asphalts  and  flux  comprising  the  asphaltic  cement 
shall,  when  required,  be  weighed  separately  in  the  presence  of 
the  authorized  inspectors  or  agents  of  the  Engineer. 

Method  of  Mixing.  Refined  asphalts  and  flux  used  in  prepar- 
ing the  cement  shall  be  melted  together  in  a  kettle  at  a  tempera- 
ture ranging  from  250°  to  not  over  375°  F.;  and  shall  be 
thoroughly  agitated  when  heated  by  air,  steam,  or  mechanical 
appliances,  until  the  resulting  cement  has  become  thoroughly 
mixed  into  a  homogeneous  mass.  The  agitation  must  be  continued 
during  the  entire  period  of  preparing  the  mixtures.  Cement  shall 
always  be  of  uniform  consistency  and,  if  any  portion  should 
settle  in  the  kettle,  between  intervals  of  using  the  same,  it  must 
be  thoroughly  agitated  before  being  drawn  for  use. 

Tests,  (a)  The  asphaltic  cement  shall  have  a  penetration  of 
from  40  to  75,  which  shall  be  varied  within  these  limits  to  adapt 
it  to  the  particular  asphalt  used  in  the  paving  mixture  and  to  the 
traffic  and  other  conditions.  The  exact  amount  of  penetration 
shall  be  fixed  by  the  Engineer. 

(b)  When  20  grams  of  the  asphaltic  cement  of  the  penetration 
to  be  used  in  the  paving  mixture  shall  be  heated  for  5  hours  at  a 
temperature  of  325°  F.,  in  an  oven  as  officially  specified,  there 
must  not  be  volatilized  more  than  5  per  cent  of  the  bitumen  pres- 


336 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         117 

ent,  nor  shall  the  penetration  at  77°  F.  after  such  heating  be  less 
than  one-half  of  the  original  penetration. 

(c)  A  briquette  of  the  asphaltic  cement,  having  a  cross  sec- 
tion of  one  square  centimeter,  when  at  a  penetration  of  50,  shall 
elongate  to  the  extent  of  not  less  than  20  centimeters  at  77°  F. 
If  the  asphaltic  cement  as  used  in  the  paving  mixture  varies  from 
50  penetration,  an  increase  of  at  least  2  centimeters  in  ductility 
will  be  required  for  each  5  points  in  penetration  above  50,  and 
a  corresponding  allowance  will  be  made  below  50  penetration. 
(Dow  method.) 

Specifications  for  Sand  and  Binder  Stone 

Sand.  The  sand  shall  be  hard  grained  and  moderately  sharp. 
It  shall  be  so  graded  as  to  produce,  in  the*  finished  surface  mix- 
ture, the  mesh  requirements  elsewhere  herein  specified.  It  shall 
contain  not  to  exceed  6  per  cent  of  sand  that  will  pass  a  No.  200 
mesh  sieve. 

Binder  Stone.  Stone  to  be  used  for  asphaltic  concrete  binder 
shall  be  hard  and  durable,  free  from  all  foreign  substances,  and 
of  uniformly  varying  sizes,  from  1  inch  down. 

Laying  the  Pavement 

Asphaltic  Concrete  Binder.  Preparation.  Asphaltic  concrete 
binder  shall  be  made  as  follows :  The  binder  stone  and  sand  as 
above  specified  shall  be  heated  to  200°-325°  F.  in  suitable  appli- 
ances. Stone  and  sand  shall  be  measured  off  separately;  and 
then  be  mixed  with  sufficient  asphaltic  cement  prepared  as  here- 
tofore specified,  in  such  proportions  that  the  resulting  aggregate 
will  contain  by  weight  material  passing  a  No.  10  mesh  screen, 
between  25  and  35  per  cent  and  bitumen  in  quantity  from  5  to  8 
per  cent  of  the  entire  mixture. 

Binder  thus  prepared  shall  be  a  compact  mass  containing  a 
minimum  of  voids. 

Laying.  The  asphaltic  concrete  binder  shall  be  brought  to 
the  work  in  wagons  covered  with  canvas  or  other  suitable  mate- 
rial, and  upon  reaching  the  street  shall  have  a  temperature  of 
200° -325°  F.  It  shall  be  placed  upon  the  concrete  foundation 
and  raked  to  a  uniform  surface  to  such  depth  that,  after  being 
rolled  and  thoroughly  compacted,  it  shall  have  an  average  thick- 
ness of  1  inch  and  shall  be  2  inches  below,  and  parallel  to,  the 
surface  of  the  finished  pavement.  The  surface,  after  compres- 
sion, shall  show  at  no  place  an  excess  of  asphaltic  cement,  and 
any  spot  covering  an  area  of  1  square  foot  or  more,  showing  au 
excess  of  asphaltic  cement,  shall  be  cut  out  and  replaced  with 


118         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

other  material.  Smaller  spots  may  be  dried  by  the  use  of  stone 
dust  and  smoothers.  Any  asphaltic  concrete  binder  broken  up 
during  the  process  of  laying  must  be  removed  and  replaced  with 
new  material.  No  more  binder  shall  be  laid  at  any  one  time  than 
can  be  covered  by  a  2  days'  run  of  the  paving  plant  on  surface 
mixture. 

Asphaltic  Surface  Mixture  or  Wearing  Course.  Specifications. 
The  surface  mixture  shall  consist  of  asphaltic  cement,  Portland 
cement  or  stone  dust,  and  sand  proportioned  by  weight,  so  that 
the  resulting  mixture  will  contain  average  proportions  of  the 
whole  mixture  as  follows: 

Bitumen  soluble  in  cold  carbon  disul- 

phide ,. 9.5  to  13.5% 

Portland  cement  or  stone  dust  pass- 
ing a  No.  200  sieve 10.0  to  15.0% 

Sand  passing  a  No.  80  sieve 18.0  to  36.0% 

Sand  passing  a  No.  40  sieve 20.0  to  50.0% 

Sand  passing  a  No.  10  sieve 8.0  to  25.0% 

Sand  passing  a  No.    4  sieve Up  to  10.0% 

NOTE. — Sieves  to  be  used  in  the  order  named. 

The  item  designated  as  "Portland  cement  or  stone  dust  pass- 
ing a  No.  200  sieve",  within  the  limits  named  herein,  includes, 
in  addition  to  the  Portland  cement  or  stone  dust,  fine  sand  passing 
a  No.  200  sieve  not  exceeding  4£  per  cent  of  the  total  mixture, 
and  such  200-mesh  mineral  dust  naturally  self-contained  in  the 
refined  asphalt. 

Mixing.  Sand  and  asphaltic  cement  shall  be  heated  separately 
to  about  300°  F.;  the  maximum  temperature  of  the  sand  at  the 
mixers  shall  in  no  case  be  in  excess  of  375°  F.  and  the  maximum 
temperature  of  the  asphaltic  cement  shall  not  exceed  325°  F.  at 
the  discharge  pipe.  The  Portland  cement  or  stone  dust  shall  be 
mixed  with  the  hot  sand  and  in  the  required  proportions;  and 
then  these  shall  be  mixed  for  at  least  1  minute,  with  the  asphaltic 
cement  at  the  required  temperature  and  in  the  proper  propor- 
tions, in  a  suitable  apparatus  so  as  to  effect  a  thoroughly  homo- 
geneous mixture. 

The  proportion  of  asphalt  cement  shall  at  all  times  be  deter- 
mined by  actual  weighing  with  scales  attached  to  the  asphaltic 
cement  bucket.  The  weight  of  the  bucket  shall  be  checked  up  at 
least  twice  every  day. 

The  Portland  cement  or  stone  dust  and  sand  must  also  be 
weighed  unless  a  method  of  gaging  approved  by  the  Engineer 
shall  be  used. 


338 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         119 

For  the  determination  of  the  temperatures  required  by  the 
specifications  throughout  the  process  of  manufacture,  the  con- 
tractor shall  provide  and  maintain  at  the  plants  suitable  regis- 
tering thermometric  instruments  to  be  approved  by  the  Engineer. 
Proper  weighing  devices  must  also  be  installed  and  maintained 
for  the  determination  of  the  quantities  of  materials  used. 

The  Contractor  shall  furnish  every  facility  for  the  verification 
of  all  scales  or  measures. 

The  sand  gradings  and  bitumen  may  be  varied  within  the 
limits  designated  at  the  discretion  of  the  Engineer. 

Laying  the  Wearing  Surface.  The  asphalt  wearing  surface 
shall  be  hauled  to  the  work  in  wagons  provided  with  a  canvas 
or  other  suitable  cover.  As  placed  in  the  street  it  shall  have  a 
minimum  temperature  of  250° -280°  F.  as  suitable  for  the  asphalt 
used.  It  shall  be  dumped  at  such  distance  from  the  work  that 
all  of  the  mixture  can  be  turned  and  distributed  to  the  place 
where  it  is  to  be  raked;  and  shall  be  spread,  while  hot,  to  such 
depth  upon  the  asphaltic  concrete  binder — which  must  be  thor- 
oughly dry,  free  from  leaves,  or  other  foreign  matter — that  after 
receiving  its  ultimate  compression  by  rolling,  it  shall  have  an 
average  thickness  of  two  inches.  The  initial  compression  shall 
be  effected  by  means  of  a  small  roller,  after  which  a  small  amount 
of  Portland  cement  or  mineral  dust  shall  be  swept  over  the  sur- 
face. Final  compression  shall  be  effected  by  a  roller  of  not  less 
than  200  pounds  per  inch  tread.  The  rolling  shall  be  carried  on 
continuously  at  the  rate  of  not  more  than  200  square  yards  per 
hour. 

All  tests  herein  provided  must  be  conducted  according  to  offi- 
cial methods  on  file  in  the  office  of  the  Chief  Engineer.  All  pene- 
trations indicated  herein,  unless  otherwise  specified,  refer  to  the 
depth  of  penetration  in  hundredths  of  a  centimeter  of  a  No.  2 
cambric  needle  weighted  to  100  grams  at  77°  F.  acting  for  5 
seconds. 

No  asphalt  shall  be  laid  when,  in  the  opinion  of  the  Engineer, 
the  weather  conditions  are  unsuitable  for  its  proper  laying;  and 
no  asphalt  shall  be  laid  unless  the  surface  on  which  it  is  to  be  laid 
is  dry. 

After  the  surface  shall  have  been  finished,  no  horse  or  vehicle 
traffic  of  any  kind  shall  be  permitted  on  the  pavement  until  it 
shall  have  hardened  sufficiently. 

Should  an  asphalt  pavement  have  to  be  laid  adjacent  to  the 
tracks  of  a  street  railroad,  granite  paving  blocks  will  be  laid  next 
to  the  track,  for  which  the  Contractor  will  be  paid  the  price 
named  in  the  proposal  for  new  granite  block  paving  upon  cement 
concrete  foundation. 


339 


120         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

The  granite  blocks  shall  be  laid  upon  a  cement  concrete  foun- 
dation, mixed  in  accordance  with  these  specifications,  which  shall 
extend  to  the  depth  of  the  bottom  of  the  crossties. 

The  top  of  the  blocks  shall  be  even  with  the  surface  of  the  tread 
of  the  rail,  which  must  conform  with  the  grade  of  the  street.  The 
blocks  shall  be  laid  before  the  wearing  surface  is  laid  upon  the 
driveway,  thoroughly  backed  with  cement  concrete,  carefully 
rammed  to  a  firm  bed.  All  joints  must  be  thoroughly  filled  with 
cement  grouting  composed  of  one  part  fresh  ground  Portland 
cement  and  one  part  clean  approved  sand. 

Asphalt-filled  manhole  covers  and  frames,  when  ordered  by 
the  Engineer,  shall  be  placed  on  all  manholes  where  such  frames 
and  covers  have  not  already  been  placed.  Payment  for  all  such 
frames  and  covers  will  be  made  at  the  prices  named  in  the 
proposal. 

WOOD=BLOCK   PAVEMENT 

Material  Specifications.  The  wood-block  pavement  layer  shall 

be inches  thick,  as  required  by  the  traffic  and  conditions 

of  the  street ;  and  constructed  of  the  materials  and  in  the  manner 
hereinafter  specified. 

Long-Leaf  Yellow  Pine.  The  wood  from  which  the  blocks  are 
made  must  be  regular,  sound,  commercial,  merchantable,  long-leaf 
yellow  pine,  which  shall  be  well  manufactured,  saw-butted,  free 
from  large  coarse  knots  or  very  coarse  grain,  and  free  from  the 
following  defects :  unsound,  loose,  and  hollow  knots,  worm  holes, 
knot  holes;  through,  round,  or  other  objectionable  shakes;  wane, 
checks,  bark;  incipient  or  other  decay. 

Other  Woods.  Other  woods,  as  Oregon  or  Washington  Doug- 
las fir,  scientifically  and  practically  equal  or  superior  to  the  above 
mentioned  long-leaf  pine,  which  can  be  equally  well  creosoted 
and  which  are  satisfactory  to  the  City  Engineer,  can  be  used,  pro- 
vided that  only  one  kind  and  quality  of  wood  is  used  on  the  same 
street  or  contract  and  further  provided  that  only  one  kind  of 
wood  is  treated  and  creosoted  at  one  time. 

Wood  Blocks.  The  paving  blocks,  cut  from  the  lumber  or 
wood  above  specified,  shall  be  well  manufactured,  truly  rectangu- 
lar, and  uniform.  They  shall  be  dressed  on  all  sides ;  except  the 
top  and  bottom,  both  of  which  shall  be  evenly  and  smoothly 
sawed.  No  block  shall  vary  in  width  and  depth  more  than  one-six- 
teenth of  an  inch  from  others  used  on  the  same  street  or  contract. 

The  depth  shall  be inches  as  already  specified.  The 

length  shall  be  not  less  than  6  nor  more  than  10  inches.  The  width 
shall  be  not  less  than  3  nor  more  than  4  inches,  provided  that  all 
blocks  used  in  one  street  or  contract  shall  be  of  the  same  width. 


340 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         121 

Creosote  Oil.  Amount  per  Cubic  Foot.  The  blocks  shall  be 
treated,  preserved,  or  creosoted  as  hereinafter  specified  and  each 
block  shall  contain  at  least  18  pounds  of  creosote  oil  per  cubic 
foot  of  wood;  or  when  a  block  contains  much  natural  pitch  it 
shall  receive  as  much  creosote  as  can  be  forced  into  it  by  the 
same  process  and  pressure  as  is  used  in  the  treatment  of  blocks 
of  the  same  kind  of  wood  which  will  receive  18  pounds  of  creosote 
oil  per  cubic  foot;  provided,  however,  that  the  combined  creo- 
sote and  natural  pitch  in  all  blocks  be  at  least  19  pounds  per  cubic 
foot. 

Quality  Tests.  The  creosote  oil  shall  be  a  dead  oil  of  coal  tar 
or  a  coal-tar  product.  It  shall  not  contain  more  than  3  per  cent 
of  water;  and  if  it  does  contain  this  amount  of  water,  a  corre- 
sponding correction  must  be  made  so  that  an  equivalent  addi- 
tional amount  of  creosote  is  forced  into  the  blocks.  It  shall 
contain  only  traces  of  acetic  acid  and  acetates.  Its  specific  gravity 
at  100°  F.  (38°  C.)  shall  be  at  least  1.03  and  not  more  than  1.10, 
so  as  to  assure  its  thoroughly  penetrating  the  wood  blocks.  It 
must  not  leave  more  than  a  trace  on  a  filter  paper  when  filtered 
between  60°  F.  and  77°  F.  Fractional  distillation  of  100  grams 
of  the  creosote  oil  shall  produce  percentages  of  dry  oil  by  weight 
within  the  following  limits: 

Up  to       150°  C.   (302°  F.)  no  distillate 

Between  150°  C.  (302°  F.)  and  170°  C.  (338°  F.)  not  to  exceed     1.5  per  cent 

Between  170°  C.   (338°  F.)  and  235°  C.   (445°  F.)  not  to  exceed  33.0  per  cent 

Between  235°  C.   (455°  F.)  and  300°  C.   (572°  F.)  not  to  exceed  35.0  per  cent 

The  residue  shall  be  soft  and  adhesive.  The  creosote  oil  shall 
contain  about  25  per  cent  of  crystallizable  naphthalene  and  at 
least  15  per  cent  anthracene  oils.  At  least  95  per  cent  of  the 
creosote  oil  shall  be  equally  soluble  in  carbon  bisulphide  and  in 
absolute  alcohol. 

Treating  the  Blocks.  Sterilizing.  The  wood  blocks,  after  being 
cut  and  ready  for  treatment,  shall  be  placed  in  a  suitable  iron 
receptacle  or  cylinder  and  there  sterilized  with  dry  steam  under  a 
pressure  of  at  least  30  pounds,  and  not  to  exceed  50  pounds  per 
square  inch  during  at  least  3  hours  and  as  much  longer,  not  to 
exceed  7  hours,  as  the  condition  of  the  wood  and  the.  season  of 
the  year  requires.  The  temperature  within  the  cylinder  during 
the  process  of  steaming  shall  be  between  250°  F.  and  280°  F.  At 
intervals  during  this  process  the  condensed  steam,  sap,  and  other 
liquid  matter  shall  be  drawn  from  the  receptacle  by  means  of 
valves.  At  the  completion  of  the  steaming  process,  all  condensed 
steam  and  other  fluid  matter  shall  be  blown  from  the  cylinder 


341 


122         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

through  an  opening  in  its  bottom,  and  the  stearn  shall  be  caused 
to  pass  out  through  an  opening  in  its  top. 

Vacuum  Treatment.  The  draining  and  exhaust  valves  of  the 
cylinder  shall  then  be  closed  and  a  vacuum  pump  shall  imme- 
diately produce,  as  quickly  as  possible,  a  vacuum  of  at  least 
24  inches,  and  as  much  more  as  may  be  necessary;  this  vacuum 
shall  be  maintained  in  the  cylinder  until  moisture  and  gases  cease 
to  come  from  the  cylinder.  During  this  process  the  wood  blocks 
•within  the  cylinder  shall  be  kept  hot  by  means  of  steam  coils 
within  it. 

Forcing  Creosote  Oil  into  the  Blocks.  Immediately  after  the 
vacuum  treatment  and  while  the  vacuum  exists,  the  creosote  oil 
at  a  temperature  between  180°  F.  and  200°  F.  shall  be  run  into 
the  cylinder  and  forced  and  maintained  under  such  pressure  that 
the  wood  blocks  shall  absorb  and  be  impregnated  with  creosote 
oil  to  the  amount  as  required  above.  The  excess  of  creosote  oil 
in  the  cylinder  shall  then  be  withdrawn;  the  blocks  drained  and 
prepared  for  shipment. 

Water  Absorption.  The  blocks  when  ready  for  use  shall  not 
absorb  more  water  than  an  average  of  44  per  cent  of  their  dry 
weight,  after  being  heated  at  100°  F.  during  12  hours  and  then 
placed  under  water  12  hours. 

Indentation  Pressure  Test.  The  blocks  ready  for  use  must 
meet  the  indentation  pressure  test  made  as  follows:  The  blocks 
to  be  tested  are  first  dried  at  100°  F.  during  12  hours.  Then  a 
polished  steel  die  of  1  square  inch  on  its  lower  face,  with  square 
edges  and  corners,  and  perpendicular  sides,  is  placed  on  a  dried 
block,  firmly  supported  in  a  compression  testing  machine.  A  pres- 
sure of  8000  pounds  is  applied  quickly  and  maintained  exactly  1 
minute.  The  die  must  not  descend  and  indent  the  block  more 
than  one-eighth  of  an  inch.  The  measurements  are  to  be  taken 
from  the  time  when  th&  die  is  lightly  pressed  against  the  block  to 
the  instant  the  8000-pound  pressure  has  been  applied  1  minute. 
The  die  is  placed  anywhere  within  one-half  inch  of  the  edges  of 
the  block  and  so  as  to  compress  lengthwise  the  wood  fibers. 

Inspection  of  Blocks.  The  wood  blocks  shall  be  inspected  by 
the  City  Engineer  at  the  place  of  manufacture,  or  on  arrival  in 
the  city  where  they  are  to  be  used,  or  when  piled  adjacent  to  the 
street  to  be  paved.  All  blocks  not  in  conformity  with  the  require- 
ments of  these  specifications  will  be  rejected  and  must  be  removed 
from  the  locality  of  the  pavement  to  be  laid. 

Laying  Blocks.  The  wood  blocks  are  to  be  laid  upon  the 
mortar  bed  immediately  after  the  said  bed  is  ready  to  receive 
them.  Except  when  otherwise  directed  by  the  City  Engineer, 
the  blocks  are  to  be  laid  with  close  joints  and  at  right  angles 


342 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         123 

to  the  curbs;  in  uniform  courses;  and  so  that  all  longitudinal 
joints  shall  be  covered  by  a  lap  of  at  least  3  inches.  No  closure  or 
end  blocks  less  than  3  inches  long  shall  be  used. 

Tight  Joints  and  Boiling.  The  blocks  shall  be  driven  or  forced 
together  as  closely  as  possible  during  laying,  and  shall  be  properly 
rolled  or  rammed  to  a  firm  bearing  and  uniform  surface. 

Defective  Blocks.  No  rolling  or  ramming  shall  be  done  within 
10  feet  of  the  surface  where  blocks  are  being  laid.  All  blocks 
which  are  broken,  split,  or  otherwise  damaged,  defective,  or  dis- 
placed shall  be  removed  immediately  after  rolling  or  ramming 
and  replaced  with  sound  blocks. 

Filling  Joints.  After  the  blocks  have  been  laid  and  properly 
rammed,  their  joints  shall  be  filled  or  grouted  with  either  a  suit- 
able bituminous  paving  joint  cement  approved  by  the  Engineer, 
or  by  a  cement  grout.  The  bituminous  cement  must  be  such  as 
not  to  be  too  soft  in  warm  weather,  and  not  too  brittle  in  cold 
weather  to  be  a  durable  and  adhesive  filler.  It  must  be  heated 
until  it  is  so  liquid  that  it  will  run  freely  into  and  fill  the  joints. 
The  cement  grout  shall  be  composed  of  two  parts  of  clean  sand 
and  one  part  of  an  approved  brand  of  Portland  cement,  mixed 
to  a  perfectly  liquid  form ;  and  the  surface  of  the  block  shall  be 
slushed  with  the  same,  and  the  joints  shall  be  swept  until  they 
are  completely  filled. 

Surface  Sand.  Immediately  after  the  grout  or  bituminous 
cement  has  filled  the  joints,  there  shall  be  spread  over  the  entire 
pavement  a  one-half-iiich  layer  of  clean,  very  coarse,  dry  sand ;  or  a 
layer  of  clean,  hard,  dry,  crushed  stone  screenings  with  particles 
not  exceeding  one-fourth  inch  and  not  smaller  than  one-thirty- 
second  of  an  inch  in  size.  This  layer  of  either  coarse  sand  or 
crushed  stone  screenings  is  to  remain  on  the  pavement  while  it  is 
subjected  to  traffic  for  a  period  of  at  least  a  month,  or  until  any 
excess  is  removed  as  far  as  possible  or  necessary  by  the  City. 

Expansion  Joints.  Expansion  joints  shall  be  constructed 
between  the  curbs  and  wood  paving  blocks  to  provide  for  the 
possible  expansion  and  contraction  of  the  blocks  by  heat  or  cold 
or  other  conditions.  These  expansion  joints  shall  be  constructed 
from  three-fourths  inch  to  1  inch  wide,  according  to  the  width  of 
the  street,  as  directed  by  the  Engineer ;  and  shall  extend  the  whole 
depth  of  the  blocks ;  and  shall  be  filled  with  a  suitable  bituminous 
paving  joint  cement  acceptable  to  the  Engineer.  Expansion  joints 
of  any  required  width  shall  be  constructed  at  such  other  locations 
as  the  Engineer  may  direct.  Expansion  joints  must  be  completely 
filled  with  suitable  strips  of  wood  previous  to  filling  the  joints  with 
the  paving  joint  cement. 

Any  bituminous  cement  adhering  to  curbs  or  sidewalks  must 


343 


124         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

be  removed  by  the  contractor.  The  pavement  and  sidewalk  shall 
be  free  from  all  surplus  materials  as  soon  as  the  Contractor  has 
finished  paving  the  street. 

GRANOLITHIC  SIDEWALK  PAVEMENTS 

Bed.  The  sidewalk  shall  be  excavated  and  graded  from  the 
curb  to  the  house  line,  or  to  the  width  required,  to  a  subgrade 
18^  inches  below  and  parallel  to  the  top  of  the  finished  pavement. 
The  bed  shall  be  thoroughly  compacted  by  ramming  to  the  pre- 
scribed lines. 

Cinder  Foundation.  On  the  subgrade  so  prepared  a  founda- 
tion of  clean,  hard  coal  cinders,  not  less  than  14  inches  thick,  shall 
be  placed  in  two  7-inch  layers,  which  shall  be  well  consolidated 
by  ramming  with  a  rammer  weighing  at  least  75  pounds,  and 
having  a  face  at  least  8  inches  square. 

The  cinders  shall  be  well  watered  during  ramming,  and  the 
top  surfaces  shall  be  brought  to  a  height  exactly  4J  inches  below 
and  parallel  to  the  finished  surface. 

Concrete  Base.  On  this  cinder  foundation  shall  be  placed  3 
inches  of  Portland  cement  concrete.  This  base  shall  be  cut  by 
joints  into  blocks  not  larger  than  6  feet  square,  the  joints  to 
extend  clear  through  the  concrete. 

Wearing  Course.  On  this  concrete  base,  and  before  the  con- 
crete has  attained  its  initial  set,  shall  be  placed  the  finished  or 
wearing  course.  This  course  shall  consist  of  a  stiff  mortar  com- 
posed of  equal  parts  of  Portland  cement  and  the  sharp  screenings 
of  crushed  granite  or  stone  of  equal  quality,  to  be  approved  by 
the  Engineer,  the  largest  particles  of  which  shall  pass  through  a 
three-eighths-inch  ring;  and  it  shall  be  free  from  dust,  loam,  or 
earthy  substances;  and  shall  be  laid  to  a  full  depth  of  1^  inches, 
carefully  floated  and  troweled  to  a  smooth,  even  surface.  A  drier 
mixed  in  the  proportion  of  1  part  sand  to  2  parts  Portland  cement 
shall  be  sprinkled  in  a  dry  state  over  the  surface,  and  then  floated 
and  troweled.  This  treatment  shall  be  repeated  3  times;  after 
which  the  joints  shall  be  cut  through  the  wearing  surface  directly 
over  the  joints  in  the  concrete  base,  troweled  with  a  small  jointer, 
and  the  entire  surface  indented  in  a  manner  to  be  approved  by 
the  Engineer. 

Tinting.  When  directed,  the  drier  mixture  shall  receive  the 
blue,  black,  or  other  tinting  matter  to  produce  the  shade  approved 
by  the  Engineer. 

Sprinkling.  When  the  pavement  is  completed,  it  shall  be  kept 
covered  for  3  days,  during  which  time  it  shall  be  kept  moist  by 
sprinkling. 


344 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         125 
BRICK  PAVEMENT 

For  brick  sidewalk  paving  the  sidewalk  shall  be  excavated  or 
filled  and  graded  from  curb  to  house  line  or  to  the  width  required ; 
and  firmly  and  uniformly  compacted,  by  ramming  or  rolling,  to  a 
subgrade  of  not  less  than  6  inches  below  the  intended  finished 
grade  of  pavement,  and  parallel  to  it.  All  soft  and  spongy  places 
shall  be  dug  out  and  properly  refilled.  Upon  the  bottom  so 
formed  shall  be  placed  a  layer  of  sharp  clean  bar  sand,  upon 
which  the  paving  brick  shall  be  laid.  The  bricks  shall  be  straight, 
hard,  first  quality  paving  bricks  laid  in  the  best  workmanlike 
manner.  Samples  of  bricks  must  be  submitted  for  approval  at 
least  10  days  before  they  are  desired  for  use. 

SODDING 

Quality  of  Sod.  The  Contractor  shall  furnish  and  place  grass 
sod  on  the  slope  of  the  embankment  and  at  other  places  as 
directed  by  the  Chief  Engineer.  The  sod  shall  be  of  good  quality 
of  earth  covered  with  heavy  grass ;  sound  and  healthy ;  free  from 
weeds ;  at  least  1  foot  square  and  2  inches  thick ;  cut  with  a  bevel 
on  the  sides  so  that  when  laid  they  will  lap  at  the  edges.  No  poor, 
lean,  or  broken  sod  will  be  allowed  in  the  work. 

Laying.  The  sod  shall  be  carefully  set  so  as  to  have  a  full 
bearing  on  their  lower  surfaces,  and  shall  be  properly  rammed 
and  well  rolled,  and  wherever  required  by  the  Chief  Engineer  they 
shall  be  pinned  down  with  wooden  pins  not  less  than  12  inches 
long.  The  surface  of  the  top  soil  shall  be  dampened  immediately 
before  laying  the  sod.  Care  shall  be  taken  to  have  all  surfaces 
conform  to  the  proper  lines  and  grades,  and  any  sliding  or  settling 
which  may  occur,  before  the  final  acceptance  of  the  work,  shall 
be  repaired  by  the  Contractor. 

Grass  sodding,  in  place,  shall  be  paid  for  at  the  price  given  in 
the  proposal. 

GENERAL  SPECIFICATIONS  FOR  THE  DESIGN  OF 
ELEVATED  TANKS  AND  STANDPIPES 

LOADS 

Definitions.  (1)  The  dead  load  shall  consist  of  the  weight  of 
structural  and  ornamental  steelwork,  platforms,  roof  construc- 
tion, piping,  etc. 

(2)  The  live  load  considered  shall  be  the  contents  of  tanks, 
the  movable  load  on  platforms  and  roofs,  and  the  wind  pressure. 

(3)  The  weight  of  water  shall  be  assumed  to  be  63  pounds 


345 


126         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

per  cubic  foot;  and  that  of  crude  oil  56  pounds  per  cubic  foot, 
1  cubic  foot  of  fluid  being  equal  to  7.48  gallons. 

(4)  The  live  loads  on  platforms  and  roofs  shall  be  taken  at 
30  pounds  per  square  foot  or  a  200-pound  concentrated  load 
applied  at  any  point. 

(5)  The  wind  pressure  shall  be  assumed  at  30  pounds  pei 
square  foot,  acting  in  any  direction.    The  surfaces  of  cylindrical 
tanks  exposed  to  the  wind  shall  be  calculated  at  two-thirds  of  the 
diameter  multiplied  by  the  height. 

(6)  The  movable  live  load  on  platforms  and  roofs  shall  not 
be  considered  as  acting  together  with  the  wind  pressure. 

UNIT  STRAINS 

Sums  of  Dead  and  Live  Loads.  All  parts  of  the  structure 
shall  be  proportioned  so  that  the  sum  of  the  dead  and  live  loads 
shall  not  cause  the  strains  to  exceed  those  given  in  Table  I. 

TABLE  I 

Maximum    Tension,    Compression,    and    Shearing    Stresses    for 
Tanks  and  Standpipes 


STRAINS  IN  VARIOUS  MEMBERS 


POUNDS  PER 
<MTARE  INCH 


Tension  in  tank  plates  (net  area) 

Tension  in  other  parts  of  structure  (net  area) 

Compression  (reduced) 

Shear  on  rivets  and  pins 

Shear  on  bolts  and  field  rivets 

Shear  in  plates  (gross  section) 

Bearing  pressure  on  rivets  and  pins 

Bearing  pressure  on  field  rivets 

Fiber  strain  in  pins 


12,000 
16,000 
16,000 
12,000 
9,000 
10,000 
20,000 
18,000 
24,000 


Compression  Factor.    For  compression  members,  the  permis- 
sible unit  strain  of  16,000  pounds  shall  be  reduced  by  the  formula 

p  =  16,000  —  70  — 

where  p  =  permissible  working  strain  in  compression,  in  pounds 

per  square  inch 

1  =  length  of  member,   from  center  to  center  of  connec- 
tions, in  inches 
r  =  least  radius  of  gyration  of  section  in  inches 


346 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         127 

The  ratio— shall  never  exceed  120  for  main  members  and  150  for 

struts. 

Wind  Stresses.  Stresses  due  to  wind  may  be  neglected  if  they 
are  less  than  25  per  cent  of  the  combined  dead  and  live  loads. 

Unit  strains  in  bracing  and  other  members  taking  the  wind 
stresses  may  be  increased  to  20,000  pounds  per  square  inch,  except 
as  shown  above. 

The  pressures  given  in  Table  II  will  be  permissible  on  founda- 
tion and  bearing  plates. 

TABLE  II 
Maximum   Allowable    Pressures   on   Foundation  and  Bearing  Plates 


FOUNDATION  MATERIAL 

TONS  PER  SQ.  FT. 

Soft  clay 
Ordinary  clay 
Dry  sand  and  dry  clay 
Hard  clay 
Gravel  and  coarse  sand 

1 

2 
3 

4 
6 

BEARING  PLATES 

LBS.  PER  SQ.  IN. 

Brickwork  with  cement  mortar 
Portland  cement  concrete 
First-class  sandstone 
First-class  limestone 
First-class  granite 

200 
350 
400 
500 
600 

DETAILS  OF  CONSTRUCTION 

Calking.  The  plates  forming  the  sides  of  cylindrical  tanks 
shall  be  of  different  diameters,  and  shall  be  calked  from  the 
inside.  No  foreign  material  shall  be  allowed  when  calking. 

In  oil-tank  work,  both  the  inside  and  the  outside  of  the  tank 
shall  be  beveled  for  calking. 

Joints.  Joints  for  horizontal  seams  and  for  radial  seams  in 
the  spherical  bottoms  of  tanks  shall  preferably  be  lap  joints. 

For  vertical  seams  lap  joints  shall  be  used  for  one-fourth-,  five- 
sixteenths-,  and  three-eighths-inch  plates ;  for  all  other  thicknesses, 
butt  joints  with  double  and  triple  rows  of  rivets  on  both  sides  of 
joint  shall  be  used. 

Rivets.  Rivets  five-eighths  inch  in  diameter  shall  be  used  for 
one-fourth-  and  five-sixteenths-inch  plates ;  rivets  three-fourths  inch 


347 


128         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

in  diameter  for  three-eighths-  to  five-eighths-inch  plates,  inclusive ; 
and  rivets  seven-eighths  inch  in  diameter  for  eleven-sixteenths-  to 
1-inch  plates,  inclusive. 

Plates.  Plates  more  than  five-eighths  inch  thick  shall  be  sub- 
punched  and  reamed. 

The  minimum  thickness  of  the  plates  for  the  cylindrical  part 
shall  be  one-fourth  inch.  The  thickness  of  the  plates  in  spherical 
bottoms  shall  never  be  less  than  that  of  the  lower  ring  in  the  cylin- 
drical part  of  the  tank. 

The  facilities  at  the  plant  where  the  material  is  to  be  fabri- 
cated will  be  investigated  before  the  material  is  ordered. 

All  plates  shall  be  punched  before  being  bevel  sheared  for 
calking. 

Spherical  Bottoms.  Radial  sections  of  spherical  bottoms  shall 
be  made  in  duplicates  of  the  number  of  columns  supporting  the 
tank,  and  shall  be  reinforced  at  the  lower  parts,  where  holes  are 
made  for  piping. 

When  the  center  of  the  spherical  bottom  is  above  the  point  of 
connection  with  the  cylindrical  part  of  the  tank,  there  shall  be 
provided  a  girder  at  said  point  of  connection  to  take  the  hori- 
zontal thrust.  The  horizontal  girder  may  be  made  in  connection 
with  the  balcony.  This  also  applies  where  the  tank  is  supported 
by  inclined  columns. 

The  balcony  around  the  tanks  shall  be  3  feet  wide  with  a  one- 
fourth-inch  floor  plate,  and  shall  have  a  suitable  railing  3  feet  6 
inches  high. 

The  upper  parts  of  spherical  bottom  plates  shall  always  be 
connected  on  the  inside  of  the  cylindrical  section  of  the  tank. 

Connections  between  Tower  Columns  and  Tank.  In  order  to 
avoid  eccentric  loading  on  the  tower  columns  and  local  stresses  in 
spherical  bottoms,  the  connections  between  the  columns  and  the 
sides  of  the  tank  shall  be  made  in  such  a  manner  that  the  center 
of  gravity  of  the  column  section  intersects  the  center  of  connec- 
tion between  the  spherical  bottom  and  the  sides  of  the  tank. 
Enough  rivets  shall  be  provided  above  this  intersection  to 
transmit  the  total  column  load. 

If  the  tanks  are  supported  on  columns,  riveted  directly  to  the 
sides,  additional  material  must  be  provided  in  the  tank  plates 
riveted  directly  to  the  columns  to  take  the  shear.  The  shear  may 
be  taken  by  providing  thicker  tank  plates  or  by  reinforcement 
plates  at  the  column  connections.  Connections  to  columns  shall 
be  made  in  such  a  manner  that  the  efficiency  of  the  tank  plates  is 
not  less  than  that  of  the  vertical  seams. 

High  Towers.  For  high  towers,  columns  shall  have  a  batter 
of  1  to  12.  The  height  of  the  tower  is  understood  to  be  the  dis- 


348 


CIVIL  SPECIFICATIONS  AND  CONTRACTS        129 

tance  from  the  top  of  the  masonry  to  the  connection  of  the 
spherical  bottom,  or  the  flat  bottom,  with  the  cylindrical  part  of 
the  tank. 

Standpipes.  The  bottom  plates  of  standpipes  shall  be  not 
less  than  five-sixteenths  inch  thick,  and  shall  be  provided  with 
tapped  holes,  1^  inches  in  diameter,  with  screw  plugs  spaced  at 
4-foot  centers  to  allow  a  filling  of  cement  on  top  of  the  masonry, 
while  the  bottom  is  being  erected,  in  order  to  secure  the  proper 
bearing. 

Near  the  bottom  of  the  standpipe  there  shall  be  provided  one 
12-  by  18-inch  manhole  of  elliptical  shape. 

Near  the  top  of  each  tank  and  standpipe  there  shall  be  pro- 
vided one  Z-bar  acting  as  a  support  for  the  painters'  trolley  and 
for  the  stiffening  of  the  tank.  The  section  modulus  of  the  same 

D2 

shall  be  not  less  than  where  Z>  is  equal  to  the  diameter  of  the 

tank,  in  feet.  If  the  upper  part  of  the  tank  is  held  by  the  roof 
construction,  this  may  be  reduced. 

Stiffening  Angles  on  Large  Tanks.  On  large  tanks,  circular 
stiffening  angles  shall  be  provided  in  order  to  prevent  the  tank 
plates  from  buckling  during  windstorms.  The  distance  between 
the  angles  shall  be  located  by  the  following  formula : 


where  d  =  approximate  distance  between  angles,  in  feet 
t  =  thickness  of  tank  plates,  in  inches 
D  =  diameter  of  tank,  in  feet 

Roof  Plates.  The  top  of  the  tank  will  generally  be  covered 
with  a  conical  roof  of  thin  plates,  and  the  pitch  shall  be  1  to  6. 
For  tanks  up  to  22  feet  in  diameter,  the  roof  plates  will  be 
assumed  to  be  self-supporting.  If  the  diameter  of  the  tank 
exceeds  22  feet,  angle  rafters  shall  be  used  to  support  the  roof 
plates. 

Plates  of  the  following  thicknesses  will  be  assumed  as  self- 
supporting  for  various  diameters:  three-thirty-seconds-inch  plate, 
up  to  a  diameter  of  18  feet ;  one-eighth-inch  plate,  up  to  a  diam- 
eter of  20  feet ;  three-sixteenths-inch  plate,  up  to  a  diameter  of 
22  feet. 

Rivets  in  the  roof  plates  shall  be  from  one-fourth  to  five-six- 
teenths inch  in  diameter  and  shall  be  driven  cold.  These  rivets 
need  not  be  headed  with  a  button  set. 

A  trapdoor,  2  feet  square,  shall  be  provided  in  the  roof  plate. 


349 


130         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Near  the  top  of  the  higher  tanks  a  platform  with  a  railing  shall 
be  provided,  for  the  safety  of  the  men  operating  the  trap- 
door. 

An  ornamental  finial  shall  be  provided  at  the  top  of  the 
roof. 

Ladder.  A  ladder  1  foot  3  inches  wide  shall  be  provided  from 
a  point  about  8  feet  above  the  foundation  to  the  top  of  the  tank, 
and  also  one  shall  be  provided  on  the  inside  of  the  tank.  Each 
ladder  shall  be  made  of  two  2J-  by  f -inch  bars  with  three-fourths- 
inch  rungs.  On  large  high  tanks,  30  feet  or  more  in  diameter,  a 
walk  shall  be  provided  from  the  column  nearest  the  ladder  to  the 
expansion  joint  on  the  inlet  pipe. 

Overrun.  In  designing  tanks,  6  inches  additional  height  shall 
be  allowed  for  overrun. 

Bracing.  The  bracing  in  the  towers  shall  not  be  adjust- 
able. 

Anchor  Bolts.  The  size  of  the  anchor  bolts  shall  be  deter- 
mined by  the  uplift  when  the  tank  or  standpipe  is  empty.  The 
unit  strains  in  the  anchor  bolts  shall  not  exceed  15,000  pounds 
per  square  inch,  and  the  minimum  section  shall  be  limited  to  a 
diameter  of  1^  inches. 

Miscellaneous.  The  concrete  shall  be  assumed  to  have  a 
weight  of  140  pounds  per  cubic  foot  and  shall  be  sufficient  in 
quantity  to  take  the  uplift. 

Any  parts  of  the  tank,  standpipe,  or  tower,  in  which  difficulties 
may  arise  in  field  riveting,  shall  be  assembled  in  the  shop,  and 
marked  properly  before  shipment. 

The  structural  material  shall  conform  to  the  "General  Speci- 
fications for  Steel  Railroad  Bridges"  as  adopted  by  the  American 
Railway  Engineering  and  Maintenance  of  Way  Association. 

The  workmanship  shall  be  in  accordance  with  the  Manu- 
facturers' Standard  Specifications  of  Feb.  6,  1903. 

Before  leaving  the  shop  all  work  shall  be  painted  with  one 
coat  of  approved  paint,  excepting  the  laps  in  contact  on  the  tank 
work.  All  parts  which  will  be  inaccessible  after  erection  shall  be 
well  painted.  After  erection,  the  structure  shall  be  covered  with 
one  coat  of  the  same  paint. 

Three-ply  frost-proof  casing  shall  be  provided,  if  necessary, 
around  the  inlet  pipe.  This  casing  shall  be  composed  of  two 
layers  of  1-  by  2^-inch  lumber,  and  each  layer  shall  be  covered  with 
tar  paper,  and  one  outside  layer  of  f-  by  2|-inch  dressed  and 
matched  flooring.  The  lumber  shall  be  in  lengths  of  about  12  feet. 
A  1-inch  air  space  shall  be  provided  between  the  layers  of  lumber, 
and  wood  rings  or  separators  shall  be  nailed  to  them  every  3  feet. 
The  frost  casing  may  be  made  square  or  cylindrical. 


350 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         131 

CONTRACT,  OR  ARTICLES  OF  AGREEMENT 

Nature  and  Purpose.  A  contract  is  an  agreement  between 
two  or  more  parties  to  do  a  certain  thing,  such  as  delivering 
material,  performing  work,  etc.,  and  is  based  upon  a  mutual 
understanding  between  the  parties  to  the  agreement  as  to  the 
nature  of  the  work  to  be  done,  the  kind  of  materials  to  be  sup- 
plied, etc.,  and  the  amount  of  the  consideration  to  be  paid. 

Everything  that  will  prevent  misunderstanding  as  to  the 
intention  of  the  parties  to  the  contract  should  be  embodied  in 
and  form  a  part  of  the  contract.  Hence,  as  already  stated,  the 
advertisement,  the  proposal,  the  drawings,  the  specifications,  and 
the  written  articles  of  agreement  should  all  form  essential  parts 
of  the  contract.  There  should  be  as  many  copies  of  the  con- 
tract executed  as  there  are  parties  to  it,  each  party  retaining  a 
copy. 

Number  of  Parties  to  a  Contract.  It  is  claimed  by  some 
authorities  that  there  can  be  but  two  parties  to  a  contract.  How- 
ever, we  have  many  examples  of  agreements  between  corpora- 
tions, where  there  are  as  many  parties  to  the  contracts  as  there 
are  interests.  There  are  also  contracts  between  financiers,  pro- 
moters, engineers,  and  contractors  often  involving  many  parties. 

ESSENTIAL  ELEMENTS 

The  four  essential  elements  of  all  contracts,  without  which  no 
contract  is  valid,  are  as  follows : 

(1)  Appropriate  parties;  or  parties  with  capacity  to  con- 
tract. 

(2)  Mutual    consent   to   the   terms   of  the   agreement— a 
mutual  understanding. 

(3)  A   definite  subject— matter  to  be  acted   on. 

(4)  A  valid  or  lawful  consideration,  actual  or  presumed— 
a  something  in  exchange  for  its  legal  equivalent. 

The  Parties.  To  every  contract  there  must  be  at  least  two 
parties,  but  there  may  be  more  than  two.  The  parties  may  be 
either  individuals,  firms,  or  corporations  and  are  designated  in 
the  agreement  as  the  party  of  the  first  part  and  the  party  of  the 


351 


132         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

second  part ;  when  there  are  other  parties,  which  is  unusual,  they 
are  designated  as  the  party  of  the  third  part  and  the  party  of  the 
fourth  part.  The  party  who  has  something  to  be  done,  or  who  is 
to  pay  the  money,  is  generally  designated  as  the  party  of  the  first 
part.  The  person  or  corporation  who  proposes  to  do  the  work 
for  a  consideration,  or  to  sell  something,  is  generally  designated 
as  the  party  of  the  second  part,  although  there  is  no  fixed  rule  in 
this  matter. 

Appropriate  Parties.  Any  person,  firm,  or  corporation  may  be 
a  competent  party.  There  are  exceptions  to  every  rule.  Generally 
corporations  may  contract  only  within  the  scope  of  their  charter 
and  by-laws  by  which  they  are  usually  limited. 

Generally  speaking,  any  person  of  sound  mind  and  legal  age 
may  make  a  contract.  There  are,  however,  exceptions  differing 
in  different  localities.  As  an  instance,  married  women  are  limited 
in  their  right  to  make  contracts  in  certain  States.  But  as  their 
powers  are  being  extended,  a  local  attorney  at  law  should  be  con- 
sulted in  making  contracts  with  them. 

A  contract  with  a  person  of  unsound  mind  is  not  binding  upon 
the  weaker  person. 

Unsoundness  of  mind  may  be  either  temporary  —  as,  from 
intoxication — or  constitutional.  When,  therefore,  there  is  the 
slightest  evidence  of  mental  unfitness,  no  contract  should  be  made, 
as  litigation  is  thereby  courted.  It  is  needless  to  say  that  a  con- 
tract should  never  be  executed  under  threat. 

Corporations.  In  a  contract,  a  corporation  is  considered  as  a 
single  individual,  regardless  of  the  number  of  its  members.  It 
is  of  the  greatest  importance  that  it  be  known  which  officers  of  a 
company  are  authorized  by  its  charter  or  by-laws  to  execute  con- 
tracts. The  president  and  the  vice-president  of  a  corporation  are 
generally  authorized  to  execute  contracts  for  their  company.  The 
execution  is  usually  witnessed  by  the  officers'  signatures  and  the 
seal  of  the  company,  attested  by  the  secretary,  the  signatures 
generally  being  acknowledged  before  a  notary  public  or  a  com- 
missioner of  deeds.  Important  contracts  shall  also  have  the 
approval  of  the  board  of  directors  of  the  company.  It  is  impor- 
tant that  the  limitation  of  the  powers  of  the  company's  charter 
be  known  before  the  contract  is  drawn. 


352 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         133 

Full  Description  of  Parties.  The  parties  to  a  contract  must  be 
so  fully  described  that  there  can  be  no  mistake  made  as  to  their 
identity.  A  firm's  full  name  and  place  of  business,  together  with 
the  names  of  the  individuals  comprising  it,  should  be  given.  An 
individual  should  be  identified  by  his  residence  and  occupation 
and  a  corporation  by  its  full  title,  and  the  name  of  the  State  or 
Country  wherein  it  was  incorporated. 

Signatures  to  Agreement.  It  is  necessary  that  the  names  of  the 
parties  used  in  the  body  of  the  agreement  be  exactly  in  accord 
with  the  signatures  at  the  end  thereof ;  discrepancies  in  the  names 
might  invalidate  the  contract. 

United  States  Government  a  Party.  The  United  States  Gov- 
ernment cannot  be  sued  for  noncompliance  with  a  contract, 
although  it  may  bring  suit  against  the  other  party  to  the  con- 
tract— so  a  State  may  not  be  sued  by  an  individual.  A  public 
official  cannot  be  held  personally  liable  for  obligations  made  by 
him  in  his  official  capacity. 

Mutual  Consent.  A  contract  is  not  legal  unless  both  parties 
thereto  have  agreed  to  the  same  thing. 

Hence  an  offer  must  be  accepted  before  it  becomes  binding 
and  until  accepted  may  be  withdrawn.  It  has  been,  said  that  an 
offer  by  letter  should  be  accepted  by  return  mail;  an  offer  by 
telegram,  by  return  telegram,  etc.  All  offers  should  be  in  writing 
to  eliminate  controversies;  therefore  they  should  be  accepted  or 
rejected  promptly. 

If  the  party  accepting  impose  any  new  conditions,  they,  in 
turn,  must  be  agreed  to  by  the  other  party,  before  a  contract  can 
be  entered  into. 

Subject  Matter.  The  subject  matter  of  a  contract  may  be 
anything  that  is  not  immoral  or  illegal,  and  it  must  concern  some 
act  to  be  carried  out.  The  subject  matter  must  be  described  so 
fully  and  clearly  that  both  parties  will  understand  all  conditions 
of  the  agreement,  as  a  contract  that  is  obscure  or  ambiguous 
leads  to  controversy  and  perhaps  litigation.  In  case  of  dispute 
as  to  the  meaning  of  the  subject  matter,  custom  and  usage  have 
great  weight  in  the.  courts. 

Consideration.  The  consideration,  or  the  price  or  reason  of 
the  promise,  should  be  clearly  and  fully  set  forth  in  the  agree- 


353 


134         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

ment.    The  consideration  makes  the  contract  legal  and  must  be 
real  and  substantial. 


ANALYSIS  OF  CONDITIONS 

Provide  for  all  Conditions.  It  is  of  great  importance  that  all 
probable  and  possible  events  in  connection  with  the  contract  be 
foreseen  and  provided  for  in  drawing  the  agreement.  It  requires 
great  experience  and  ability  to  be  able  to  foresee  and  provide  for 
all  conditions  that  may  arise  in  the  course  of  the  work.  It  is, 
therefore,  best  for  the  Engineer  to  follow  the  standard  form  of 
some  acknowledged  authority  until  he  becomes  experienced  in 
contract  drawing,  making  such  changes  as  are  necessary  to  suit 
his  conditions. 

Duties  of  Parties.  Each  contract  must  stand  on  its  own  basis ; 
that  is  to  say,  where  the  work  to  be  done  is  legal;  methods  of 
doing  it  legal;  the  parties  making  it  competent  to  act;  and  the 
agreement  set  forth  in  writing.  The  agreement  so  made  becomes 
law*  between  the  parties.  In  case  of  disputes  the  courts  can 
only  construe  contracts,  so  as  to  determine  what  the  intentions 
of  the  parties  were;  hence  the  necessity  of  the  contract  specifi- 
cally setting  forth  the  duties  and  obligations  of  the  respective 
parties  thereto.  It  must  be  remembered  that  though  the  Engineer 
draws  the  contract,  the  courts  may  be  called  upon  to  construe  it. 

Guaranty.  A  guaranty  in  the  form  of  a  bond  or  certified 
check  is  generally  required  of  bidders  on  public  works.  This  is 
to  reimburse  the  owner  for  the  cost  of  re-advertisement  and  delay 
in  case  the  successful  bidder  fails  to  execute  the  contract,  and  to 
compensate  for  loss  or  damages  incident  to  delay  in  completion 
of  the  work,  caused  by  the  failure  of  the  bidder. 

Bond.  A  surety  bond,  to  enter  into  contract,  should  be  re- 
quired of  the  Contractor  on  all  contracts  for  public  works,  and 
on  all  other  important  contracts  (the  amount  of  such  bond  being 
set  forth  in  the  notice  to  bidders),  for  the  faithful  performance 
of  the  contract  and  prompt  payment  for  labor  and  material,  and 
as  a  protection  to  the  Company  against  all  damage  to  persons  or 
property  caused  by  negligence  of  the  Contractor  or  his  employes. 

In  some  contracts  for  public  works,  one  bond  is  required  to 


354 


CIVIL  SPECIFICATIONS  AND  CONTEACTS         135 

cover  the  performance  of  the  contract;  another  one  to  protect 
the  material,  men,  and  labor;  and  still  others,  covering  other 
requirements  due  to  local  laws.  There  is  no  rule  for  the  amount 
of  the  bond  to  be  given  by  the  Contractor.  Bonds  must  generally 
be  sued  upon  in  order  to  recover,  throwing  the  burden  of  proof 
upon  the  Company. 

Payment  Clauses.  In  the  payment  clauses  in  the  contract, 
under  various  conditions,  the  Engineer  is  authorized  to  withhold 
payment  until  the  objectionable  conditions  are  removed  by  the 
Contractor.  It  is,  therefore,  sometimes  considered  that  a  "with- 
held payment"  is  one  of  the  best  means  of  securing  the  desired 
end — the  old  story  of  "touching  a  man's  pocketbook"  to  gain 
results.  The  withheld  payment  throws  the  burden  of  proof  on 
the  Contractor,  in  case  of  dispute ;  is  simple  and  direct,  and,  there: 
fore,  easy  of  application.  It  has  been  said  with  truth  that  "the 
guaranty  of  good  work  is  intelligent  and  faithful  inspection,  with- 
held payments,  and  the  Contractor's  bond." 

Arbitrators.  The  employment  of  the  arbitration  clause  is  not 
to  be  recommended,  as  in  case  of  controversies  it  is  rare  that  the 
parties  to  the  contract  will  abide  by  the  conditions  of  the  arbitra- 
tion clause,  generally  preferring  to  throw  the  dispute  into  the 
courts,  rather  than  trust  their  interests  to  the  unknown  qualifica- 
tions of  arbitrators. 

They  may  decline  even  to  appoint  arbitrators.  If,  however, 
each  party  appoints  an  arbitrator  to  act  in  the  matters  of  con- 
troversy and  executes  an  instrument  agreeing  to  abide  by  the 
decision  of  the  arbitrators  chosen,  according  to  the  terms  of  the 
contract,  they  are  irrevocably  bound  by  the  findings  of  the  board. 
The  following  clause  has  been  used  by  the  writer  in  a  few  cases : 

Arbitration.  In  the  case  of  any  difference  or  dispute  arising 
between  the  Company  and  the  Contractor,  during  the  execution 
of  the  work,  other  than  the  meaning  of  the  specifications  and 
drawings,  which  shall  be  interpreted  by  the  Engineer,  the  same 
shall  be  referred  to  3  disinterested  arbitrators,  one  to  be  appointed 
by  each  of  the  parties  to  this  contract  and  the  third  by  the  two  thus 
chosen,  the  decision  of  any  2  of  whom  shall  be  final  and  binding 
on  the  parties  thereto;  and  cost  and  expenses  of  said  arbitration, 
including  reasonable  witness  fees,  shall  be  imposed  upon  either 
of  the  parties  hereto,  or  divided  between  said  parties  in  an  equi- 


355 


136         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

table  manner  by  the  arbitrators,  and  shall  be  paid  by  said  party 
or  parties  in  accordance  with  the  arbitrators'  decisions. 

Manufactured  Products.  In  contracts  involving  the  supply  of 
manufactured  materials  such  as  structural  steel  or  building 
materials,  when  the  party  supplying  same  is  subject  to  strikes, 
floods,  etc.,  a  clause  such  as  the  following  is  often  inserted  in  the 
contract  to  limit  the  liability  of  the  Contractor,  and  is  considered 
equitable. 

Strikes,  Floods,  etc.  The  times  herein  mentioned  for  comple- 
tion of  the  work  are  subject  to  delays  due  to  transportation, 
strikes,  fires,  floods,  storms,  or  other  causes  beyond  the  Con- 
tractor's control.  Should  the  work  be  delayed  by  any  of  the 
foregoing  causes,  the  Contractor  shall  have  additional  time,  not 
less  than  the  extent  and  sum  of  said  delays,  in  which  to  complete 
his  work  under  this  contract.  This  extension  of  time  shall  be 
commensurate  with  the  specified  excusing  cause  or  causes. 

NOTE. — Local  Laws.  The  local  lien  and  labor  laws  should  be  most  care- 
fully looked  into  before  the  drawing  of  a  contract.  They  are  different  in  dif- 
ferent States.  Some  prescribe  the  hours  of  labor  and  amount  of  pay  for 
workmen;  others  provide  that  the  person  furnishing  the  materials  of  construc- 
tion and  the  laborers  shall  have  a  preferred  claim  to  that  of  the  Contractor; 
still  others  require  that  the  contract  be  filed  with  some  official,  to  prevent  seri- 
ous and  expensive  legal  disputes  among  the  owner,  contractor,  material  men, 
sub-contractors,  laborers,  etc.  Too  much  importance  cannot  be  given  to  the 
drawing  and  filing  of  contracts  where  the  local  lien  and  labor  laws  are  in 
force.  Local  customs  and  usages,  in  the  matter  of  measuring  plaster,  brick 
work,  masonry  of  different  kinds,  etc.,  must  be  provided  against  in  the 
contract. 


FORMS  OF  AGREEMENT 

In  preparing  a  form  of  agreement,  it  is  well  to  have  a  list  of 
the  various  essentials  to  a  well-drawn  civil  engineering  contract 
before  the  writer,  in  order  to  avoid  the  omission  of  important 
clauses.  The  following  provisions  should  be  included  in  the 
agreement : 

Opening  Clause.  A  correct  form  for  the  opening  clause. 
There  are  many  forms  that  are  correct  and  it  is  not  material 
which  is  used.  To  make  the  form  more  readily  understood,  names 
and  dates  in  the  examples  given  below  have  been  filled  in. 


356 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         137 

THIS  AGREEMENT,  Made  and  Entered  Into  this *??*?» 

day  of .^ly ^   in  the  year  of  Qur  Lord  191  4 ^  by 

and  between. ....^®.e?...M°.H?.^a.inRailroad  ComPany»  a  corporation 
created  by  and   existing  under   the   laws  of   the  State   of 
New  Jersey,    and  having   its   principal   office   at   509   South 
Broad  Street,    in  the  City  of  Newark, 

in  said  State,  hereinafter  called  "Company",  party  of  the  first 
part;  and     Smith  ,_Jonest   anc*  c.omPany?   °?  *h.e.  City  of 
Chicago,    State  of  Illinois,   a  firm  composed  of  John  G. 
Smith,   James  S.   Jones,   and  William  F.   Brown,   having  its 
principal  place  of  business  at  14  South  Front  Street,   in 
the  City  of  Chicago,   and  State  of  Illinois, 
party  of  the  second  part,  hereinafter  called  the  "Contractor", 
"Witnesseth : — 

or 

ARTICLES   OF   AGREEMENT,    Made   and   Concluded   this 

tenth day  of July }  A    D    191  4 ?  by  and 

between  Brooklyn  Terminal  Company,    a  corporation  created 
by  and  existing  under  the  laws  of  the  State  of  New  York, 

and  having  its  principal  office  at ,18  South i  Water ...Str_eet_f_ 

in  the  Borough  of  Brooklyn,   City  of  New  York,   in  the  said 
State,   hereinafter   called  "Company", 

party  of  the  first  part;  and.-J«»e^D-?l^.^?t^*^ 
residing  at  710  Burns  Avenue,    in  .the  City  of  Boston,   State 

of  Massachusetts, 

party  of  the  second  part,  hereinafter  called  the  "Contractor", 

Witnesseth : — 

Parties.  It  is  advisable  to  designate  the  parties  to  the  con- 
tract for  the  sake  of  brevity  by  one  word  as :  Company,  Engineer, 
Contractor,  Agent,  Trustee,  Owner,  Purchaser,  Incorporate,  Board, 
City,  etc..  as  the  case  may  be. 

Arrangement  of  Clauses.  Following  the  opening  clauses 
should  come  the  specific  covenants  and  agreements  of  the  respec- 
tive parties  to  the  contract,  which  should  be  set  forth  as  clearly 
and  unequivocally  as  possible. 

Plans  and  Specifications.     Where  the  plans  and  specifications 


357 


138         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

are  properly  drawn  they  should,  of  course,  show  the  quantity 
and  quality,  and,  as  far  as  possible,  the  amount  of  work  to  be 
done,  material  to  be  furnished,  and  the  time  and  method  of  mak- 
ing payments ;  also  the  time  of  beginning  and  of  completing  the 
work,  and  other  details  of  the  operation;  hence  the  articles  of 
agreement  must  specifically  state  that  the  work  and  labor  to  be 
done,  and  materials  to  be  furnished  and  delivered,  must  be  in 
strict  and  exact  accordance  with  the  proposal,  plans,  and  speci- 
fications attached  to  the  Articles  of  Agreement  which  are  made 
a  part  of  the  contract. 

Materials,  Workmanship,  and  Damages.  Usually  the  Articles 
of  Agreement  should  also  state  that  the  materials  and  workman- 
ship are  to  be  the  best  of  their  kinds,  and  should  provide  for 
the  proper  inspection  thereof;  for  their  approval  or  rejection;  for 
the  replacing  of  defective  material  or  workmanship ;  for  a  time 
within  which  the  work  should  be  performed;  and  for  a  specific 
stipulation  that  upon  failure  of  the  Contractor  to  complete  the 
work  within  the  time  specified,  a  fixed  sum  shall  be  deducted  from 
the  contract  price  for  each  and  every  day  that  the  work  remains 
incomplete,  as  ascertained  and  liquidated  damages  and  not  as  a 
penalty. 

In  fixing  the  amount  of  liquidated  damages  for  each  day's 
delay,  due  consideration  should  be  given  to  the  actual  loss  to  the 
Company  for  such  delay,  as  courts  are  inclined  to  look  with  dis- 
favor upon  anything  in  the  nature  of  a  penalty. 

Prosecution  of  Work.  The  Articles  of  Agreement  should  also 
contain  a  covenant  for  due  prosecution  of  the  work,  and  should 
provide  means  and  methods  by  which  the  Company  may  proceed 
to  furnish  the  materials  or  complete  the  work  upon  the  failure  or 
neglect  of  the  Contractor  to  comply  with  the  terms  of  the 
contract. 

Surety.  It  should  also  provide  for  the  entry  of  security  for  the 
proper  performance  of  the  contract  by  bond  or  otherwise.  Per- 
sonal bonds  should  be  avoided  whenever  possible,  and  good  surety 
company  security  accepted  instead.  The  bond  is  a  very  important 
factor  in  the  contract  and  the  clause  should  be  very  carefully 
drawn  and  in  such  a  manner  (if  it  is  possible)  that  the  necessary 
changes  in  plans  and  specifications  may  be  made  without  vitiating 
the  bond.  It  is  of  the  greatest  importance  that  before  any 
changes  or  alterations  are  made,  the  person  or  surety  company 


358 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         139 

on  the  Contractor's  bond  be  notified  of  the  Engineer's  intention, 
and  their  consent  obtained  before  proceeding  with  the  work. 

Protective  Clause.  It  should  further  provide  for  proper  pro- 
tection of  the  work  and  precautions  against  accidents  and  an 
assumption  of  liability  by  the  Contractor  of  all  damages  to  per- 
sons or  property  resulting  from  the  prosecution  of  the  work. 
Provision  should  be  made  against  assigning,  transferring,  or 
subletting  the  contract;  and  should  specify  that  it  is  subject  to 
all  local  laws  regulating  the  employment  of  workmen  and  the 
protection  of  material  men  and  sub-contractors ;  and  for  the  pro- 
tection of  the  Company  the  contract  should  contain  an  appropriate 
clause  drawn  in  accord  with  the  local  laws  waiving  the  right  of 
the  Contractor,  material  men,  laborers,  or  sub-contractors  to  file 
liens.  This  last  covenant  should  be  drawn  by  a  local  attorney ;  in 
most  instances  the  contract  should  be  filed  in  accordance  with 
the  law  of  the  place  where  the  work  is  to  be  done. 

Contract  Price.  The  Agreement  should  also  contain  the 
amount  to  be  paid  and  method  of  payment. 

Special  Clauses.  The  Articles  of  Agreement  may  properly 
contain  special  clauses  providing  for  the  handling  of  different 
contingencies  that  may  arise  in  the  performance  of  the  work; 
and  it  is  the  duty  of  the  Engineer  to  foresee  all  possible  complica- 
tions that  may  arise,  and  to  provide  means  of  protecting  the 
parties  in  case  of  such  complications. 

The  specifications  usually  provide  for  extra  work,  alterations 
in  plans  and  specifications,  and  settling  of  disputes ;  in  which  case, 
special  reference  to  the  plans  and  specifications,  etc.,  renders  it 
unnecessary  to  refer  again  to  them  in  the  Agreement ;  but  if  the 
specifications  do  not  so  provide,  special  clauses  should  be  inserted 
in  the  agreement. 

Date.  The  contract  may  be  dated  in  either  the  beginning,  or 
the  closing  clauses,  or  both.  It  is  not  well  to  write  out  the  date 
in  full  in  both  clauses. 

Seals.  As  already  stated,  when  corporations  are  parties  to 
contracts  the  corporate  seal  should  be  attached.  When^  indi- 
viduals are  parties  to  contracts  a  scroll  around  the  word  "seal" 
written  with  ink  is  generally  considered  sufficient.  The  initials  of 
the  signer  should  be  written  across  the  "seal". 


359 


140         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Witness.  A  notary  public  is  the  best  witness  to  a  contract, 
as  it  is  easy  to  locate  him  and  prove  his  authority  in  case  of  doubt 
as  to  the  authenticity  of  the  signature. 

Conclusion.  The  usual  wording  for  the  conclusion  of  the 
agreement  is: 

IN  WITNESS  WHEREOF,  the  -parties  herein  named  have  here- 
unto set  their  hands  and  seals,  the  day  and  year  herein  first 
above  named. 


of  the  first  part) 

President 
Attest  :    [SEAL] 


^^ 

C/  C/  Secretary 


Witnesses : 

)  /3  ) 

- - [SEAL] 

[SEAL] 


Jarty  of  the  second  part) 
Contractor 

TYPICAL  AGREEMENTS 

The  following  forms  of  agreement  will  be  of  service  to  the 
student.  The  order  in  which  the  clauses  are  arranged  is  not  vital, 
and  none  of  the  forms  contain  all  of  the  suggested  clauses,  so  the 
Engineer  in  drawing  the  agreement  must  be  governed  by  the  con- 
ditions surrounding  the  work  and  the  parties. 

General  Form 

THIS   AGREEMENT,    Made    this  ...........  t»??ty-?A9°?*  ............  day 

of  ..........  ?.?P.1i??l?®?  ..........  in  the  year  of  our  Lord  one  thousand  nine 

hundred   and  .............  *.??_  .........  (191...°  .......  ),    between   the  ........  P.*1*0.  ..........  .. 

Railroad  Company,  a  corporation  of  the  State  of  Ohio, 

hereinafter  called  the  party  of  the  first  part,  and  ...^trick  ........ 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         141 

^  Washington  Avenue, 

City  of  Wilmington,   State  of  Delaware, 

hereinafter  called  the  part...?  .......  of  the  second  part, 

WITNESSETH,  That  the  said  part...?  .......  of  the  second  part,  for  and 

in  consideration  of  the  payments  hereinafter  specified  and  agreed 
to  be  made  to  --------  t^C^traotor  ------------  by  the  gaid  party  of  the 

first   part,    hereby   covenant...3..'.  .....  contract...8.?.  .....  and   agree...3?     to 

furnish  and  deliver  all  the  materials,  and  to  do  and  perform  all 
the  work  and  labor  required  to  be  furnished  and  delivered,  done 
and  performed  in  .....  ***QQ*^^ 


Extension  of  the  Ohio  Railroad  from  Greenburg  to  Graytown, 
all  in  the  State  of  Ohio,    including  grading,   masonry,  build- 
ings,   track,    and   signals,    complete    and   ready    for    opera- 
tion,   all 

in  strict  and  exact  accordance  with  the  proposal  and  specifica- 
tions hereto  attached,  which  said  proposal  and  specifications  are 
hereby  made  a  part  of  this  agreement  as  fully  to  all  intents  and 
purposes  as  though  herein  set  out  at  length. 

The  said  part...?  .......  of  the  second  part  further  contract-3.  _______ 

and  agree...3  ......  that  all  of  the  materials  used  in  the  said  work 

shall  be  of  the  best  of  their  several  kinds  and  qualities,  and  that 
all  of  the  said  materials  and  work  shall  be  subject  to  the  inspec- 
tion and  approval  of  the  .....  ^*L^^^°^*£J**^°**  ......  _ 

.c..?.m.Pa?.y..  ________________________________________  and  in  case  any  of  the  said  materials 

or  work  shall  be  rejected  by  the  said  ____  Chief_Engineer  --- 

as  defective  or  unsuitable,  then  the  said  materials  shall  be  re- 
placed with  other  materials,  and  the  said  work  shall  be  done 
anew  immediately,  to  the  satisfaction  and  approval  of  the  said 
............  C^ef  .  En^ine.er  .............  at  the   cost  and  expense   of  the  said 

part..?.  .......  of  the  second  part. 

It  is  further  distinctly  understood  and  agreed  that  the  said 
work  shall  be  completed  on  or  before  the  .........  ?!?_st____day___of  ..... 

January,   nineteen  hundred  and  twelve   (1912)  ........  an(j  jf  the  said 

work  be  not  completed  within  the  time  specified,  it  is  understood 
and  agreed  that  the  sum  of.  ...................  ^ejttadted  ...........  Dollarg 

($  .............  100  ...............  )  per  day  shall  be  deducted  from  the  amount 

due  the  said  part...?.  ______  of  the  second  part  for  each  and  every  day 

the  said  work  shall  remain  incomplete  or  unfinished  after  the 
said  time,  not  as  a  penalty,  but  as  ascertained  and  liquidated 


361 


142         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

damages;  which  sum  so  deducted  shall  remain  the  property  of 
the  said  party  of  the  first  part.  Or  shall  the  said  part....?...  of  the 

second  part  in  the  opinion  of  the  said Chief.  ?ngine.er 

be  prosecuting  the  said  work  with  an  insufficient  stock  of  mate- 
rials for  the  prompt  completion  thereof  within  the  specified  time, 

or  be  improperly  performing  the  said  work,  or  shall *?.® 

Contractor neglect  or  abandon  it  before  com- 
pletion or  unreasonably  delay  the  same,  so  that  the  conditions 
of  the  contract  are  being  wilfully  violated  or  carelessly  executed, 

or  in  bad  faith,  or  shall. *?.?..  Contractor neglect  or  refuse 

to  renew  or  again  perform  such  work  as  may  be  rejected  by  the 

said Chief  Engineer as  defective  or  unsuitable,  or  shall 

.^..Contractor in  any  other  manner  in  the  opinion  of 

the  said phief  ..Engineer make  default  in  the  perform- 
ance of  this  contract,  then  and  in  any  such  case  the  said. C_hi_ef 

EM*?.8.6.?! shall  promptly  notify  the  said  part..?.. 

of  the  second  part  in  writing  of  such  neglect  or  default.  If 
such  notification  be  without  effect  within  twenty -four  hours  after 

the  delivery  thereof,  then  and  in  that  case  the  Baid_j5M5£ 

EM*.n.e.e£ may  notify  the   said  part...y of   the 

second  part  to  discontinue  all  work  under  this  contract;  and  the 

said ^i?.L^&e?l. shall  thereupon  have  full  authority 

and  power  immediately  to  purchase  such  materials,  tools,  and 

machinery,  and  to  employ  such  workmen  as  in h.i? 

opinion  shall  be  required  for  the  proper  completion  of  the  said 

work  at  the  cost  and  expense  of  the  said  part...y of  the  second 

part  or .hi?. surety,  or  both;  or  the  said ChA®?. 

Engineer may,  without  notice,  declare  this  con- 
tract null  and  void,  and  the  security  bond  and  the  retained  per- 
centage and  the  material  delivered  and  used  in,  on,  or  about 
the  said  work  shall  then  become  the  property  of  the  said 
Railroad  Company. 

The  said  part..^. of  the  second  part  further  contract...?. and 

agree ...? to  properly  enclose  the  said  work,  and  to  place  signal 

lights  thereon  all  night,  when  and  where  necessary,  and  to  be 
responsible  for  and  pay  all  loss  or  damage  to  either  person  or 
property  which  may,  in  any  manner,  arise  by  reason  of  the  prose- 
cution of  the  said  work,  during  the  progress  of  t'he  same,  and  in 
case  of  the  happening  of  such  loss  or  damage  the  amount  thereof 
may  be  retained  by  the  said  party  of  the  first  part  out  of  any 
payments  due  or  to  grow  due  hereunder. 


362 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         143 

The  said  part...? of  the  second  part  agree...? not  to  assign, 

transfer,  nor  sublet  this  contract. 

It  is  further  understood  and  agreed  that  this  contract  is  en- 
tered into  under  and  subject  to  the  provisions  of  the  various  local 
laws  in  regard  to  Sub-Contractors,  Security,  and  Workmen. 

In  consideration  of  the  premises,  the  said  party  of  the  first 

part  agrees  to  pay  to  the  said  part...? of  the  second  part 

Two  hundred  and  fifty  thousand  dollars  ($250,000.). 

It  is  further  distinctly  understood  and  agreed  that  the  total 
amount  to  be  expended  for  the  materials  to  be  furnished  and 
work  to  be  done  under  this  contract  shall  in  no  event  exceed  the 
sum  of  Tw?  kund.re<I  and  seventy-five  thousand  ($275,000. ) 

dollars. 


PASTIES  HEREIN  NAMED  HAVE  HEREUNTO  SET  THE1E 
HANDS  AND  SEALS,  THE  DAY  AND  TEAK  HEREIN  FIRST 
ABOVE  NAMED, 


Attest  :  OHIO  RAILROAD  COMPANY, 

[CORPORATE  SEAL] 


OHIO  RAILROAD  COMPANY, 
By  SL§^  ........... 

^  President 


\^  Secretary 

Witnessed  by  ..................................................................  [SEAL] 

.  ....................  [SEAL] 

Contractor 
Railway   Form 

As  already  stated,  there  is  a  great  difference  of  opinion  as 
to  whether  certain  clauses  be  placed  in  the  agreement  or  the 
specification. 

There  are  many  conditions  affecting  contracts  that  an  engi- 
neer generally  does  not  appreciate.  It  is  advisable,  therefore,  to 
submit  the  contract  and  bond  before  execution  to  an  attorney, 
for  advice  as  to  whether  all  the  requirements  of  the  law  have 
been  complied  with. 

The  following  form  of  agreement  is  that  used  by  one  of  the 


144         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

great  trunk  lines  of  the  country,  for  their  contracts  for  Grading, 
Masonry,  Trestlework,  Tunnels,  etc. 

ARTICLES    OF   AGREEMENT,    Made    and   concluded   this 

„ t?e?ty  rlf.rst day  of J.™e. A.  D.  191  A*. 

by  and  between     Fas^  ^ine  ?ailroa!*  PomPany'  a  corporation 
of  the  State  of  New  Jersey, 

of  the  first  part,  and !^55?iJ*!^^  

corporation 

Of     the  S^M6...  °L.Ne*.^.e.rs?y  • 

second  part. 

WITNESSETH,  that  for  and  in  consideration  of  the  covenants 
and  payments  hereinafter  mentioned  to  be  made  and  performed 

by  the  said  party  of  the  first  part,  the  said PH.*?. of  the 

second   part  hereby   covenant...? and   agree...?. subject   to   the 

approval  and  to  the  satisfaction  and  acceptance  of  the  Chief 

Engineer  of  the  said  rail .r°al.....  Company  .....J.0...^.1.1.!!11.6. _ 

J5^^S!2iE±J^_^5_^25U?ilHJ^^»to  do  and  to  finish  in 
a  substantial  and  workmanlike  manner,  and  in  strict  conformity 
with  the  annexed  specifications,  hereby  adopted,  accepted,  and 
declared  by  the  parties  hereunto  to  be  an  essential  part  of  this 

agreement,  the  entire  work  of M ^M. .9.9? .f. "dans , ,___exoa- 

vat  ing  same  to_hard_rpck  bottom,   and  building  all  the  piers 

and  abutments  of  the  Green  River  Bridge 

And  it  is  mutually  agreed  between  the  said  parties  of  the  first 
and  second  parts,  that 

1.  Right  of  Way.     The  right  of  way  and  use  of  such  lands  as 
may  be  necessary  to  enable  the  said  party  of  the  second  part  to 
conform  to  the  requirements  of  the  specifications  here  attached 
shall  be  furnished  for  the  construction  of  the  said  railway  by  the 
said  party  of  the  first  part,  so  that  the  work  herein  contracted 
for  can  be  promptly  commenced  and  prosecuted  to  completion. 

2.  Work  Executed  under  Direction  of  Chief  Engineer.     The 
work  shall  be  executed  under  the  supervision  and  direction  of 
the  Chief  Engineer  of  the  party  of  the  first  part   (hereinafter 
called  the  Chief  Engineer,  being  either  the  regular  incumbent  of 
the  office  of  Chief  Engineer,  or  the  person  who,  from  time  to 
time,   may  be  designated  by  the  party  of  the  first  part  to  be 
Acting  Chief  Engineer).    Such  Chief  Engineer  shall  possess  and 
exercise  all  the  power  hereinafter  prescribed,  and  shall  designate 
the  portions  of  the  line  upon  which  work  shall  be  begun  and  per- 
formed, and  shall,  at  all  proper  times,  furnish  plans,  measure- 


364 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         145 

ments,  stakes,  and  directions  for  doing  the  work,  it  being  dis- 
tinctly understood  that  any  action  herein  contemplated  as  to  be 
taken  by  the  Chief  Engineer  may  be  taken  and  performed,  sub- 
ject to  his  ultimate  approval  and  adoption,  by  his  subordinates, 
and  when  so  taken  and  performed  shall,  upon  such  approval  and 
adoption  (but  not  otherwise),  be  in  all  respects  taken,  treated, 
and  considered  as  the  sole  and  original  action  of  the  Chief  Engi- 
neer. Oral  instructions  in  regard  to  any  work  to  be  performed 
under  this  agreement,  if  accepted  by  the  said  party  of  the  second 
part,  shall  be  accepted  at  his  own  risk,  and  no  instructions  so 
given  shall  relieve  the  said  party  of  the  second  part  from  liability 
to  damages  or  expenses  arising  from  the  performance  of  the  work 
in  accordance  with  such  instructions,  or  in  any  other  way  than 
in  accordance  with  this  agreement,  and  the  said  party  of  the 
first  part  hereby  reserves  to  itself  the  right  to  accept  or  reject 
any  or  all  work  done  in  accordance  with  such  instructions. 

3.  Tools,  Materials,  Mechanics,  Laborers  at  Contractor's  Ex- 
pense.   The  said  party  of  the  second  part  shall,  at  his  own  expense, 
cost,  and  charge,  find  and  provide  a  full  and  ample  supply  of  the 
best  and  most  suitable  tools  and  appliances  required  to  be  used 
in  the  performance  of  said  work,  and  provide  the  best  of  mate- 
rial of  every  kind  that  may  be  needed  for  the  thorough  and  expe-. 
ditious  execution  of  said  work,  and  shall  furnish  and  provide  in 
sufficient  numbers  all  mechanics,  laborers,  and  other  workmen, 
and  also  all  things  that  may  be  necessary  and  requisite  for  con- 
structing and  completing,  within  the  time  herein  stipulated,  the 
whole  Of  the  work  herein  agreed  to  be  done. 

4.  Time  of  Commencement  and  Completion.     The  work  herein 

contracted   for  shall  be   commenced  within IME*? days 

after  the  date  of  this  agreement,  and  shall  be  completed  on  or 

before .^.Y. _ik?JL_ 191....6. This  stipulation  being 

made  with  the  full  knowledge,  understanding,  and  agreement  by 
the  party  of  the  second  part  that  the  time  of  commencement,  dis- 
continuance, suspension,  resumption,  and  rate  of  progress  of  any 
and  all  work  contemplated  in  or  by  this  contract,  shall  be  subject 
and  according  to  such  directions  as  may,  from  time  to  time,  be 
given  by  the  Chief  Engineer,  and  that,  unless  expressly  so  de- 
clared in  writing  by  the  Chief  Engineer,  the  date  of  final  com- 
pletion shall  not  be  postponed  by  reason  of  any  such  direction,  or 
any  compliance  therewith ;  and  no  right  of  the  party  of  the  first 
part  under  any  clause  of  this  contract,  nor  any  obligation  or 
liability  of  any  contractor,  surety,  or  bondsman  shall  be  waived, 
lost,  or  impaired  by  any  extension  of  the  time  for  performance 
beyond  the  date  above  fixed  for  completion,  but  every  clause  of 


365 


146         CIVIL  SPECIFICATIONS  AND  CONTRACTS 


the  contract  or  bond  shall  apply  in  respect  of  the  time  as  extended 
by  the  written  declaration  of  the  Chief  Engineer. 

5.  Prices.  For  and  in  consideration  of  the  true  and  faithful 
performance  of  the  work  by  the  said  party  of  the  second  part, 
according  to  the  agreements  and  conditions  contained  in  this 
agreement,  and  the  specifications  hereto  attached,  the  said  party 
of  the  first  part  hereby  promises  and  agrees  to  pay,  in  the 
manner,  at  the  times,  and  under  the  conditions  hereinafter  pro- 
vided, to  the  said  party  of  the  second  part,  his  executors  or  admin- 
istrators, for  the  work  done  and  materials  furnished  as  aforesaid, 
at  the  following  rates  and  prices,  to  wit : 


For  clearing,  per  acre 50  00 

For  grubbing,  per  acre 250  00 

GENERAL  EXCAVATION  AND  EMBANKMENT 

For  solid  rock,  per  cubic  yard 0  85 

For  loose  rock,  per  cubic  yard 0  60 

For  earth,  per  cubic  yard 0  30 

For  borrowed  embankment,  per  cubic  yard 0  25 

For  excavation   without   classification,    per    cubic 

yard 0  38 

For  removing  old  masonry,  per  cubic  yard 1  50 

EXCAVATION  IN  WATER 

For  solid  rock,  per  cubic  yard 2  80 

For  loose  rock,  per  cubic  yard 2  00 

For  earth,  per  cubic  yard 1  00 

For  excavation  without  classification,  per  cubic 

yard 2  50 

TUNNEL  EXCAVATION 

For  single  track  tunnels,  per  cubic  yard 4  00 

For  double  track  tunnels,  per  cubic  yard 3  75 

For  shafts,  per  cubic  yard 6  00 

BALLAST 

For  broken  stone,  per  cubic  yard,  in  place  under 

track  well  surfaced 1  20 

For  gravel,  per  cubic  yard,  in  place  under  track 

well  surfaced 1  05 

For  slag,  per  cubic  yard,  in  place  under  track 

well  surfaced.  .  1  15 


CENTS 


366 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         147 


MASONRY 


For  1st  class,  per  cubic  yard 10  00 

For  2d  class,  per  cubic  yard 8  00 

For  3d    class,    or    rubble,    and    box    culverts,    in 

cement,  per  cubic  yard 6  00 

For  3d  class,  or  rubble,  and  box  culverts,  dry,  per 

cubic  yard 3  50 

For  arch  masonry,  1st  class,  per  cubic  yard 12    j    00 

For  arch  masonry,  2d  class,  in  cement,  per  cubic 

yard 10  25 

For  arch  masonry,  2d  class,  dry,  per  cubic  yard. .  2  75 

For  slope  walls,  per  cubic  yard 2    !    75 

For  stone  paving,  in  cement,  per  cubic  yard 3  50 

For  stone  paving,  dry,  per  cubic  yard 3  00 

For  concrete  No.  1,  per  cubic  yard 8  50 

For  concrete  No.  1,  per  cubic  yard,  f -in.  stone,  per 

cubic  yard 8  65 

For  concrete  No.  2,  per  cubic  yard 7  75 

For  brick  work,  per  cubic  yard 12  00 

For  packing  in  cement,  per  cubic  yard  (in  tun- 
nel)   6  00 

For  packing,  dry,  per  cubic  yard  (in  tunnel) 4  25 

For  packing,  dry,  per  cubic  yard  (back  of  abut- 
ments and  retaining  walls) 2  75 

For  rip-rap,  per  cubic  yard 1  95 

MACADAM  AND  TELFOED  EOADWAY 

For  Macadam  paving,  per  square  yard 0  85 

For  Telf ord  paving,  per  square  yard 0  93 

IEON  DEAIN  PIPE 

For    4-inch,  per  lineal  foot  in  place 0  55 

For    6-inch,  per  lineal  foot       ' '        0  80 

For    8-inch,  per  lineal  foot       "         0  95 

For  10-inch,  per  lineal  foot       "         1  10 

For  12-inch,  per  lineal  foot       "        1  25 

For  16-inch,  per  lineal  foot      ""        1  95 

For  20-inch,  per  lineal  foot       "        

For  24-inch,  per  lineal  foot       "         

For  30-inch,  per  lineal  foot       "        4  95 

For  36-inch,  per  lineal  foot       "         6  80 

For  48-inch,  per  lineal  foot       "         n  30 

For  60-inch,  per  lineal  foot       "        16   I   85 


CENTS 


367 


148 


CIVIL  SPECIFICATIONS  AND  CONTRACTS 


TERRA  COTTA  DRAIN  PIPE 


For  4-inch, 
For  6-inch, 
For  8-inch, 
For  10-inch, 
For  12-inch, 
For  15-inch, 
For  18-inch, 
For  20-inch, 
For  24-inch, 
For  27-inch, 
For  30-inch, 
For  36-inch, 


per  lineal  foot  in  place, 

per  lineal  foot  " 

per  lineal  foot  " 

per  lineal  foot  " 

per  lineal  foot  " 

per  lineal  foot  " 

per  lineal  foot  " 

per  lineal  foot  " 

per  lineal  foot  " 

per  lineal  foot  " 

per  lineal  foot  " 

per  lineal  foot  " 

FOUNDATION  TIMBER 


For  White  Oak,  per  1000  feet  B.  M.  in  place 

For  Yellow  Pine,  per  1000  feet  B.  M.     "        

For  Hemlock,  per  1000  feet  B.  M 

TRESTLE  TIMBER 

For  White  Oak,  per  1000  feet  B.  M.  in  place 

For  Yellow  Pine,  per  1000  feet  B.  M.     "        

For  Hemlock,  per  1000  feet  B.  M.          "       

TUNNEL  TIMBER 

For  White  Oak,  per  1000  feet  B.  M.  in  place 

For  Yellow  Pine,  per  1000  feet  B.  M.     "        

For  Hemlock,  per  1000  feet  B.  M.          "       

PILING 

For  White  Oak,  per  lineal  foot  left  in  the  work . . 
For  Hemlock,  per  lineal  foot  ' '         " 

For  Yellow  Pine,  per  lineal  foot         "         " 

TRACK  LAYING 

For  track  laying  and  lining,  including  unloading 
of  track  materials,  spacing  of  ties,  and  plac- 
ing in  position  of  switches  and  frogs,  complete, 
per  mile  single  track 

STEEL  AND  IRON  WORK 

For  wrought  iron,  per  pound  in  place,  spikes,  bolts, 
etc 

For  steel,  per  pound  in  place,  inetal  for  reinforcing 
concrete  

For  cast  iron,  per  pound  in  place 


DOLLARS 

CENTS 

0 

40 

0 

70 

1 

00 

1 

12 

1 

29 

1 

56 

1 

82 

2 

10 

2 

67 

3 

77 

4 

45 

6 

10 

51 

00 

53 

00 

52 

00 

60 

00 

55 

00 

53 

00 

49 

00 

45 

00 

43 

50 

0 

48 

0 

32 

0 

36 

860 

00 

0 

04 

0 

04 

0 

03 

368 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         149 

6.  Payment.  During  the  progress  of  the  work,  so  long  as 
the  party  of  the  second  part  shall  fully  comply  with  the  terms  of 
the  agreement,  the  party  of  the  first  part  shall,  upon  or  about 
the  15th  day  of  each  calendar  month,  and  at  such  place  as  may 
from  time  to  time  be  designated  by  the  Chief  Engineer,  make  to 
the  party  of  the  second  part  an  advance  payment  for  and  on 
account  of  the  work  done  and  material  furnished  during  the 
preceding  calendar  month ;  quantity,  character,  and  value  of  such 
work  and  material  to  be  estimated  and  certified  by  the  Chief 
Engineer  or  by  his  subordinates,  with  his  written  approval ;  such 
advance  payment  not  to  exceed  ninety  per  cent  of  the  value  as 
thus  estimated  and  certified.  Such  certificate  may  be  based  on 
either  actual  measurements  or  simple  estimate,  or  both  com- 
bined, as  shall  be  approved  by  the  Chief  Engineer  and,  except  as 
otherwise  determined  by  the  Chief  Engineer,  no  amount  so  esti- 
mated and  certified,  nor  any  amount  shall  in  any  wise  be  deemed 
payable,  nor  shall  the  same  in  any  manner  be  transferable  or 
assignable  either  by  the  act  of  the  party  of  the  second  part  or  by 
the  operation  of  law  as  a  subsisting  debt  or  liability  of  the  party 
of  the  first  part,  until  the  final  estimate  shall  have  been  made 
and  become  payable  as  hereinafter  provided,  nor  (except  at  the 
option  of  the  party  of  the  first  part)  until  all  amounts  payable 
to  laborers,  sub-contractors,  or  material  men  shall  have  been  fully 
paid,  or  the  payment  thereof  secured  to  the  satisfaction  of  the 
Chief  Engineer.  The  portion  of  each  amount  so  certified  (being 
not  less  than  a  sum  equal  to  ten  per  cent  thereof)  reserved  by  the 
party  of  the  first  part  shall  be  by  it  retained  forever  as  com- 
pensation for  or  on  account  of  any  damages  which  may  be  certi- 
fied by  the  Chief  Engineer  to  have  been  by  it  sustained  from 
any  failure  of  the  party  of  .the  second  part  to  perform  this  contract, 
and  the  work  thereunder,  as  herein  provided;  but  any  part 
thereof  not  required  as  such  compensation  shall  be  payable  and 
paid  to  the  same  persons  at  the  same  time  and  upon  the  same 
conditions  as  the  final  payment  under  this  contract,  hereinafter 
provided  for.  And  it  is  further  provided  that,  at  the  discretion 
of  the  Chief  Engineer,  a  larger  proportionate  part  than  ten  per 
cent  of  each  monthly  certificate  may  be  retained  by  the  party 
of  the  first  part  as  a  protection  against  overpayment  for  work 
done,  as  compared  with  that  remaining  to  be  done;  and-  at  all 
times  it  shall  be  wholly  discretionary  with  the  party  of  the  first 
part  to  make  any  payments  on  account  of  material  delivered,  and 
not  permanently  applied  to  the  work  for  which  it  may  have  been 
intended. 

Each  monthly  estimate,  unless  it  be  specifically  decided  and 
therein  declared  in  writing  to  the  contrary  by  the  Chief  Engineer, 


150         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

shall  cover  and  certify  the  quantity,  character,  and  value  of  all 
work  done  or  material  furnished  since  the  last  preceding  esti- 
mate, which  shall  by  the  Chief  Engineer  be  considered  as  extra 
work,  and  the  acceptance  by  the  party  of  the  second  part  of  ttoe 
amount,  payable  under  any  monthly  estimate,  shall  be  deemed 
and  taken  (except  as  to  that  part  of  the  price  thereof  being  not 
less  than  ten  per  cent  reserved  and  retained  by  the  party  of  the 
first}  part  as  compensation  as  aforesaid)  as  a  waiver  by  him 
of  any  and  all  claim  for  or  on  account  of  extra  work  up  to  that 
time,  and  each  monthly  estimate  or  certificate  of  the  Chief  Engi- 
neer shall,  unless  expressly  therein  provided  to  the  contrary,  be 
final  and  conclusive  as  to  any  and  all  extra  work  rendered  or 
claimed  to  have  been  rendered  at  any  time  prior  to  the  close  of 
the  month  for  which  such  estimate  or  certificate  shall  be  given. 

7.  Monthly  Estimates  Conclusive  Only  for  the  Time  Being,  and 
Subject  to  Variation.     Every  monthly  estimate  shall,  for  the  time 
being  be  conclusive  upon  both  parties  hereto,  but  being  made 
(except  as  above  provided  as  to  extra  work)  merely  as  a  basis 
for  payment  on  account,  though  with  a  great  desire  and  effort 
for  accuracy,  may  be  only  approximately  correct,  and  therefore 
shall  (except  as  above  provided  as  to  extra  work)  be  subject  to 
correction  by  the  Chief  Engineer  in   any  subsequent   monthly 
estimate,  or  in  any  final  estimate ;  and  no  such  monthly  estimate 
or  certificate  for  unfinished  work  shall  be  considered  or  taken  as 
an  acceptance  of  the  work,  or  as  a  release  of  the  said  party  of 
the  second  part  from  responsibility  therefor,  nor  as  controlling  the 
Chief  Engineer  in  the  final  certificate,  which  alone  shall  operate 
as  an  acceptance  of  the  work  or  as  a  release  of  the  party  of  the 
second  part. 

8.  Final  Estimates  and  Payments.    When  this  agreement  in 
all  its  parts  and  in  the  manner  therein  provided  shall  have  been 
completely  performed  on  the  part  of  the  said  party  of  the  second 
part,  and  such  performance  shall  have  been  accepted  and  so  cer- 
tified in  writing  by  the  said  Chief  Engineer,  a  final  estimate  of 
the  quantity,  character,  and  value  of  the  work  done  and  materials 
furnished,  according  to  the  terms  of  this  agreement,  shall  be  made 
by  the  Chief    Engineer,  and  thereupon  and  not  otherwise   or 
sooner,   except  at  its  own  election,  the   said  party  of  the  first 
part  shall  within  90  days  thereafter,  pay  to  the  said  Contractor, 
upon   his    giving    a   release    under   seal   to   the    said   party   of 
the  first  part  from  all  workmen  and  material  men,  of  all  claims 
or   demands  whatsoever   growing  in   any  manner  out   of  this 
agreement,    all  sums  of  money  so   certified  by  the   Chief  Engi- 
neer to  be  then  remaining  due  and  unpaid  upon  the  work  per- 
formed under  this  agreement,   after  first  deducting  therefrom 


370 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         151 

any  and  all  sums  herein  provided  to  be  retained  by  the  said  party 
of  the  first  part,  it  being  expressly  understood  that  such  final 
estimate  and  certificate  of  the  Chief  Engineer  shall  be  conclusive 
upon  the  parties  to  this  contract. 

And  it  is  further  distinctly  understood  and  agreed : 

1.  Must  Obtain  Consent  to  Sublet.    The  said  party  of  the  sec- 
ond part  shall  not  assign  or  sublet  the  whole,  or  any  part  of  this 
agreement   (for  any  work  to  be  done  thereunder)   without  first 
having  obtained  the  consent,  in  writing,  of  the  said  part  of  the 
first  part  thereto. 

2.  If  at  any  time  during  the  progress  of  the  work  it  shall 
appear  to  the  Chief  Engineer  (a)  that  the  work  does  not  progress 
with  reasonable  speed;  or  (6)  that  the  force  employed,  the  quan- 
tity or  quality  of  the  tools,  appliances,  or  workmen  provided,  or 
wrork  done  or  materials  furnished  are  not  respectively  such  as  to 
insure  the  completion  of  the  work  within  the  agreed  time,  or 
are  not  in  accordance  with  the  specifications  hereto  annexed;  or 
(c)  that  the  party  of  the  second  part  has  unreasonably  failed  to 
pay  laborers  and  workmen  or  overseers  for  work  performed  under 
this  agreement;  or  (d)  that  legal  proceedings  have  been  instituted 
by  parties  other  than  the  party  of  the  first  part,  against  the 
party  of  the  second  part  in  such  manner  as  to  interfere  with  the 
prosecution  of  the  work,  or  to  subject  the  party  of  the  first  part 
in  making  further  payments  under  this  contract  to  the  peril  of 
litigation  or  outside  claims ;  or  (e)  that  the  party  of  the  second  part 
is  failing  in  any  manner  of  substance  to  observe  and  perform 
this  contract;  then,  and  in  any  of  such  events,  such  fact  or  con- 
dition may  be  fully  ascertained  and  declared  by  the  Chief  Engi- 
neer, over  his  signature,  in  a  writing  to  be  filed  with  the  party 
of  the  first  part,  and  a  copy  thereof  shall  be  served  upon  the 
party  of  the  second  part,  either  in  person  or  by  mailing  the  same 
to  him  at  the  address  by  him  last  given  to  the  party  of  the  first 
part,  or  by  posting  the  same  on  the  door  of  his  office  on  or  near 
the  work,  and  at  any  time  after  the  service  as  aforesaid  of  such 
certificate  of  the  Chief  Engineer  may  take  any  of  the  following 
courses : 

(a)  Penalty.  The  Chief  Engineer  may,  by  a  writing  simi- 
larly served  (of  which  a  copy  shall  be  filed  with  the  party  of 
the  first  part),  declare  this  contract  terminated  and  annulled, 
and  from  the  time  of  such  service  this  agreement,  and  every  part 
thereof,  shall  cease  and  terminate,  and  shall,  as  to  all  further 
action  or  right  thereunder  (including  any  right  of  the  party  of 
the  second  part,  or  any  one  claiming  under  him,  to  receive  the 
unpaid  value  of  any  work  done),  become  null  and  void,  except 
that  all  sums  theretofore  reserved  by  the  party  of  the  first  part 


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152         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

shall  belong  to  and  be  retained  by  the  party  of  the  first  part 
as  liquidated  compensation  receivable  by  the  party  of  the  first 
part  for  the  damages  not  susceptible  of  exact  ascertainment 
caused  the  party  of  the  first  part  by  such  failure  of  the  party  of 
the  second  part;  or, 

(&)  Penalty.  The  Chief  Engineer  may,  by  a  writing  simi- 
larly served  (of  which  a  copy  shall  be  filed  with  the  party  of 
the  first  part),  declare  that  the  party  of  the  second  part  has 
grossly  violated  this  contract,  and  that  the  contract  is,  therefore, 
forfeited  and  the  party  of  the  second  part  in  gross  default,  in  which 
event  the  party  of  the  second  part  shall  have  no  further  right  under 
this  contract,  or  concerning  any  work  theretofore  done  there- 
under, but,  nevertheless,  he  and  his  sureties  shall  compensate  the 
party  of  the  first  part  for  any  and  all  loss  or  damages  which 
may,  from  time  to  time,  be  certified  by  the  Chief  Engineer  to  have 
in  any  wise  resulted  from  such  gross  violation,  ascertained  as 
aforesaid;  or, 

(c)  Penalty.  The  Chief  Engineer  may  by  a  writing  simi- 
larly served  (of  which  a  copy  shall  be  filed  with  the  party  of 
the  first  part),  require  the  party  of  the  second  part  to  at  once 
supply  such  increase  of  force,  appliances,  or  tools,  and  to  cause 
to  be  made  such  improvements  in  the  character  of  the  work  and 
material  as  may  be  required  in  the  opinion  of  the  Chief  Engineer, 
to  make  the  same  conform  to  the  stipulations  of  this  agreement 
and  the  specifications ;  and  if,  on  the  expiration  of  ten  days  after 
such  service  of  such  writing,  the  party  of  the  second  part  shall  have 
failed  to  furnish  to  the  party  of  the  first  part  evidence  satis- 
factory to  the  Chief  Engineer  of  the  intention  and  ability  of  the 
party  of  the  second  part  to  furnish  the  desired  improvements 
and  remedy  the  specified  deficiencies,  the  said  party  of  the  first 
part  may  thereupon  enter  on  and  take  possession  of  the  said 
work,  or  any  part  thereof,  with  the  tools,  materials,  plants,  appli- 
ances, houses,  machinery,  and  other  appurtenances  thereon,  and 
hold  the  same  as  security  for  any  or  all  damages  or  liabilities 
that  may  arise  by  reason  of  the  non-fulfillment  of  this  agreement 
within  the  time  herein  stipulated ;  and,  furthermore,  may  employ 
the  said  tools,  materials,  etc.,  as  aforesaid,  and  such  other  means 
as  the  said  party  of  the  first  part  may  deem  proper  to  complete 
the  work  at  the  expense  of  the  said  party  of  the  second  part,  and 
may  deduct  the  cost  of  completing  the  entire  work  from  any  pay- 
ments then  due  or  thereafter  falling  due,  to  the  said  party  of 
the  second  part,  and  recover  from  him  and  his  sureties  any  and  all 
deficiency. 

And  immediately  upon,  from,  and  after  the  service,  as  afore- 
said, of  any  of  the  three  writings  last  mentioned,  all  right  of 


372 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         153 

occupancy  in  or  upon  any  lands  or  property  of  the  party  of  the 
first  part;  and  all  rights  of  the  party  of  the  second  part,  or  of 
any  person  claiming  under  or  through  him  any  further  prosecu- 
tion of  or  interest  in  the  work  shall  cease  and  determine,  and  the 
party  of  the  first  part  may  take  possession  of  such  lauds  or 
property  and  complete  the  work  thereon  in  such  manner  and  by 
such  means  as  it  may  think  best. 

And  it  is  further  agreed  and  understood  that  if,  at  any  time, 
the  party  of  the  second  part  shall  refuse  or  neglect  to  prosecute  the 
work  with  a  force  sufficient,  in  the  judgment  of  the  Chief  Engi- 
neer, for  its  completion  within  the  time  specified,  then,  and  in 
that  case,  the  party  of  the  first  part  may  proceed  to  employ 
such  a  number  of  workmen,  laborers,  and  overseers  as,  in  the 
opinion  of  the  Chief  Engineer,  may  be  necessary  to  insure  the 
completion  of  the  work  within  the  time  hereinbefore  limited,  at 
such  wages  as  the  party  of  the  first  part  may  find  necessary 
or  expedient,  and  may  pay  all  persons  so  employed  and  charge 
all  amounts  so  paid  as  so  much  money  paid  to  the  party  of  the 
second  part  under  this  contract. 

It  is  further  agreed  and  understood  that  if  the  said  party  of 
the  second  part  shall  not  complete  the  said  work  within  the  time 
herein  specified,  and  the  said  party  of  the  first  part  shall,  not- 
withstanding such  failure,  permit  the  said  party  of  the  second  part 
to  proceed  with  or  complete  th'e  said  work  as  if  such  time  had  not 
elapsed,  such  permission  shall  not  be  deemed  a  waiver  in  any 
respect,  by  the  said  party  of  the  first  part,  of  any  forfeiture 
or  liability  for  damages  or  expenses  thereby  incurred  arising  from 
such  noncompletion  of  the  said  work  within  the  time  specified, 
but  such  forfeiture  or  liability  shall  still  continue  in  full  force 
against  the  said  party  of  the  second  part  as  if  such  permission  had 
not  been  granted.  And  it  is  further  distinctly  understood  and 
agreed,  that  time,  whenever  involved  in  this  agreement,  is  of  the 
essence  of  this  agreement. 

3.  Nonpayment  of  Wages.  In  all  cases  of  nonpayment  by 
the  said  party  of  the  second  part  of  any  sum  or  sums  of  money  due 
the  laborers  or  other  workmen,  for  work  performed  under  this 
agreement,  the  said  party  of  the  first  part  is  hereby  authorized 
to  pay  such  laborers  or  workmen  the  amounts  due  and  owing  to 
them  by  the  said  party  of  the  first  part;  and  if  any  action  or 
proceeding  at  law  or  in  equity  shall  be  instituted,  by  virtue  of 
any  law  or  statute  now  in  force,  or  hereafter  enacted,  for  labor 
and  wages  on  said  work,  the  said  party  of  the  first  part  may 
pay  all  damages,  wages,  recoveries,  costs,  expenses,  and  counsel 
fees  arising  therefrom,  and  deduct  the  same,  and  also  whatever 
amounts  may  be  paid  for  wages  as  before  mentioned,  from  any 


373 


154         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

moneys  due  or  to  grow  due  to  the  said  party  of  the  second  part ; 
and  the  said  party  of  the  first  part  may,  from  time  to  time, 
retain  such  reasonable  sums  as  it  may  deem  necessary  for  its 
protection  in  this  behalf,  and  the  said  party  of  the  second  part  shall 
forthwith  pay  to  the  party  of  the  first  part  the  amount  of  any 
deficiency  arising  from  such  payment  of  laborers  or  other  work- 
men, and  the  retention  from  time  to  time  of  such  reasonable  sums 
as  it  may  deem  necessary  for  its  protection  in  this  behalf,  and  the 
said  party  of  the  second  part  shall  pay  the  deficiency  arising  there- 
from upon  demand. 

4.  Discharge  of  Employes  for  Cause.     The  said  party  of  the 
second  part  shall  discharge  any  foreman  or  other  employe  who 
shall,  in  the  judgment  of  the  said  Chief  Engineer,  be  unfaithful, 
unskillful,  or  remiss  in  the  performance  of  his  work,  or  guilty 
of  riotous,  disrespectful,  or  otherwise  improper  conduct;  and  no 
person  so  discharged  from  this  work,  or  any  other  work  done  for 
the  said  party  of  the  first  part,  shall  be  employed  again  by  the 
said  party  of  the  second  part  upon  the  work  to  be  done  under 
this  agreement,  without  the  written  consent  of  the  said  Chief 
Engineer. 

5.  Use  of  Intoxicants.     The  use  or  sale  of  ardent  spirits,  or 
other  intoxicating  beverages  upon  the  work,  or  in  any  of  the 
buildings,   boarding   houses,    or   other   tenements   owned,    occu- 
pied, or  within  the  control  of  the  said  party  of  the  second  part, 
or   any   of   his   employes,    is   strictly   forbidden,    and    the    said 
party  of  the  second  part  shall  exercise  his  influence  and  au- 
thority to   the   utmost   extent   to   secure   compliance   with   this 
regulation. 

6.  Contractors  to  be  Held  Responsible  for  Violations  of  Laws 
and  Ordinances.     In  all  operations  connected  with  the  work  em- 
braced in  this  agreement  the  said  party  of  the  second  part  shall  be 
held  responsible  for  any  failure  to  respect,  adhere  to,  and  comply 
with  all  local  ordinances  and  laws  controlling  or  limiting,  in  any 
way,  the  actions  of  those  engaged  upon  the  work,  or  affecting 
the  materials,  or  the  transportation  or  disposition  of  them.    And 
the  said  party  of  the  second  part  hereby  assumes  all  liability  for, 
and  agrees  to  indemnify  the  said  party  of  the  first  part  against 
all  loss,  cost,  or  damages  for  or  by  reason  of  any  liens,  claims, 
or  demands  for  materials,  or  from  laborers,  mechanics,  and  others, 
and    from    any    damages    arising    from    injuries    sustained    by 
mechanics,  laborers,   or  other  persons,  by  reason  of  accidents 
or    otherwise,     and    from    damages    sustained    by    depositing 
materials  to  public  injury,   or  to  the  injury  of  any  person  or 
corporation,    including    costs    and    expenses    of    defense,    pro- 
vided that  he  be  duly  notified  of  the  bringing  of  suits  in  such 


374 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         155 

cases,  and  be  permitted  to  defend  the  same  by  his  own  counsel, 
if  he  should  so  elect. 

7.  Contractor  to  be  Responsible  for  Damages.     Where  the  line 
of  the  railway  passes  through  farms,  the  said  party  of  the  second 
part  shall  keep  up  such  temporary  fences  as  may  be  necessary 
for  the  preservation  of  the  crops  thereon.    The  said  party  of  the 
second  part  shall  be  responsible  for  any  damages  that  may  be  done 
by  him  or  his  workmen  during  the  performance  of  this  work  to 
property  adjacent  to  the  line,  in  consequence  of  his  or  their  un- 
skillfulness  or  negligence ;  and  if  any  such  damage  shall  be  done, 
the  said  Chief  Engineer  shall  have  the  right  to  settle  and  pay 
the  same ;  and  deduct  the  amount  thereof  from  the  payments  to 
be  made  upon  the  estimates.     Whenever  any  work  herein  em- 
braced shall  in  any  manner  interfere  with  a  public  or  private 
traveled  road,  the  said  party  of  the  second  part  shall  keep  a  tem- 
porary roadway,   during  such  interference,   at  all  times  unob- 
structed and  safe  for  travel,  and  any  damages  which  may  result 
from  failure  so  to  do  may  be  settled  and  withheld,  as  above,  until 
paid  by  the  said  party  of  the  second  part. 

8.  Material  and  Labor  Not  Provided  for  in  Specification  to  be 
Done  and  Furnished  on  Written  Order  of  Chief  Engineer.     If,  in 
the  course  of  the  performance  of  this  contract,  or  any  work  there- 
under, it  shall,  according  to  the  written  opinion  of  the  Chief 
Engineer,  become  necessary  for  the  party  of  the  second  part  to  do 
any  work  or  to  furnish  any  material  not  embraced  in  the  fore- 
going classification,  or  for  which  no  price  is  hereinbefore  speci- 
fied, then  and  in  that  event  the  party  of  the  second  part  shall,  if 
ordered  in  writing  by  the  Chief  Engineer,  under  and  according 
to  his  directions,  do  all  such  work,  and  furnish  all  such  material, 
and  upon  performance  to  the  satisfaction  of  the  said  Chief  Engi- 
neer, the  party  of  the  second  part  shall  at  the  periods  and  in  the 
manner  herein  provided  for  payments  under  the  contract,  receive 
therefor  the  reasonable  value  thereof,  as  the  same  shall  be  ascer- 
tained and  determined  by  the  Chief  Engineer,  at  approximately 
the  rate  of  payment  above  fixed  for  work  or  material   (if  any 
such  there  be)  of  substantially  similar  character;  or,  at  the  dis- 
cretion of  the  Chief  Engineer,  a  separate  contract  for  such  work 
and  material  (if  any)  may  be  entered  into  by  the  party  of  the 
first  part  with  any  person,  and  the  person  so  contracting  shall 
be  permitted  free  access  and  facility  in  performing  such  work 
and  furnishing  such  material,  it  being  intended  hereby  to  ex- 
clude, as  far  as  possible,  any  claim  for  "extra"  work  (so-called), 
and  to  provide  for  the  most  prompt,  expeditious,  and  econom- 
ical prosecution  of  all  work  necessary  to  the  principal  under- 
taking. 


375 


15G         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

9.  Chief  Engineer  May  Alter  Line,  Location,  etc.     The  said 
Chief  Engineer  shall  have  the  right  to  make  any  alteration  that 
may  hereafter  be  determined  upon  by  him  as  necessary  or  desir- 
able in  the  location,  line,  grade,  plan,  form,  or  dimensions  of  the 
work,  either  before  or  after  the  commencement  of  the  same,  de- 
fined in  writing,  and  by,  or  without  drawings;  and  in  case  such 
alterations  increase  the  quantities,  the  said  party  of  the  second  part 
shall  be  paid  for  such  excess  at  the  contract  rates  herein  speci- 
fied; but  should  such  alterations  diminish  the  quantity  or  extent 
of  the  work  to  be  done,  they  shall  not,  under  any  circumstances, 
be  construed  as  constituting  and  shall  not  constitute  a  claim  for 
damages,  on  any  ground  whatever,  nor  shall  any  claim  be  made 
on  account  of  anticipated  profits,  nor  on  any  account  whatever 
in  respect  to  the  work  which  may  be  altered  or  dispensed  with, 
the  intent  of  this  provision  being  that  only  the  work  absolutely 
done  shall  be  paid  for,  and  at  the  prices  named  in  this  agreement. 

10.  Claim  for  Extra  Work.     No  claim  for  extra  work  shall, 
under  any  circumstances,  be  made,  allowed,  or  considered,  unless 
the  same  shall  have  been  done  in  pursuance  of  an  order  given  in 
writing,  as  above  provided,  by  the  said  Chief  Engineer;  but  noth- 
ing shall  be  deemed  or  construed  as  extra  work  which  can  be 
classified,    measured,    and    estimated   under   the    terms    of    this 
agreement. 

11.  Allowance  for  Delays.     No  extra  compensation  shall  be 
made  to  the  said  party  of  the  second  part  for  hindrances  or  delays 
from  any  cause  in  the  progress  of  any  portion  of  the  work  per- 
formed under  this  agreement;  but  if  such  delays  or  hindrances 
arise  from  any  cause  other  than  the  fault  of  the  said  party  of  the 
second  part,  then  and  in  that  case,  the  said  party  of  the  second  part 
shall  be  entitled  to  such  extension  of  time  for  the  completion  of 
this  contract  as  shall,  in  the  opinion  of  the  said  Chief  Engineer, 
be  sufficient  to  compensate  for  any  such  detention,  provided  the 
said  party  of  the  second  part  shall  give  notice,  in  writing,  to  the 
said  party  of  the  first  part  of  such  hindrances  and  delays,  stat- 
ing the  cause  thereof,  within  twenty-four  hours  after  the  same 
shall  first  occur. 

12.  Right   to   Suspend   Work.     The   said  party   of  the  first 
part  reserves  the  right  to  suspend  or  terminate  the  work  em- 
braced in  this  agreement  for  reasons  not  herein  specified,  and  the 
said  party  of  the  second  part  hereby  agrees  to  discontinue  all  work 
within  ten  days  after  receiving  notice  of  such  suspension  or  ter- 
mination, in  which  case,  the  said  party  of  the  second  part  shall  be 
entitled  to  payment  in  full  for  all  materials  actually  handled  or 
supplied,  at  a  valuation  to  be  fixed  by  the  Chief  Engineer,  sub- 
ject to  review,  as  hereinafter  provided,  but  shall  make  no  claim 


376 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         157 

for  consequential  damages  or  anticipated  profits  upon  work  not 
actually  performed  or  damage  of  any  kind  resulting  from  such 
suspension  or  termination. 

13.  Repairs  in  Case  of  Defective  Work.     Any  replacement  or 
repairs  rendered  necessary  upon  or  about  the  work  herein  con- 
tracted for,  by  reason  of  defective  material  or  workmanship  fur- 
nished or  performed  by  the  said  party  of  the  second  part,  shall  be 
made  by  the  said  party  of  the  second  part  upon  demand,  without 
cost  or  expense  to  the  said  party  of  the  first  part. 

14.  Chief  Engineer  to  Settle  Disputes.     All  questions,  differ-  , 
ences,  or  controversies  which  may  arise  between  the  parties  hereto 
in  regard  to  any  work  to  be  done  under  this  agreement,  whether 
as  to  its  performance  or  non-performance,  or  in  any  way  what- 
ever pertaining  to  or  connected  with  said  work,  shall  be  referred 
to  the  said  Chief  Engineer,  and  his  decision  shall  be  in  the  nature 
of  an  award,  and  shall  be  final  and  conclusive  upon  both  parties, 
and  compliance  on  the  part  of  the  party  of  the  second  part  with 
every  such  decision  of  the  Chief  Engineer  shall  be  a  condition 
precedent  to  the  right  to  receive  any  payment  hereunder. 

15.  Modification   of   Contract.     This  contract,   and   any   and 
every   provision   thereof,   may   be   modified   or  extended   by   the 
mutual  agreement  of  the  parties  hereto. 

16.  Security.     The  contractor  will  be  required  to  give  an  ap- 
proved trust  company's  bond  in  the  sum  of  one-half  the  amount 
or  approximate  amount  of  the  Contract,  for  the  faithful  execution 
and  completion  of  the  work. 

IN  WITNESS  WHEREOF,     The  parties  herein  named  have 
hereunto  set  their  hands  and  seals,  the  day  and  year  herein  first 
above  named. 
Attest  : 


FAST  LINE  RAILROAD  COMPANY, 


President 


RELIANCE  CONTRACTING  .COMPANY , j-L>  s>] 

[SEAL]  By.  VjkXkfc^sA^  s.] 

Contractor 
Attest : 


Secretary 


377 


158         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

The  following  "Directions  as  to  Execution  of  Contracts"  are 
issued  by  the  United  States  Government  in  connection  with  some 
of  its  contracts,  and  may  be  studied  to  the  advantage  of  the 
student  of  this  subject: 

1.  The  papers  should  be  made  in  quadruplicate,  and  each 
copy  should  be  the  exact  counterpart  of  the  others,  so  that  any 
one  of  them  may  be  used  as  an  original. 

2.  Before  signatures  are  appended  to  the  papers,  all  dates 
should  be  written  in,  and  all  remaining  blank  spaces  ruled  out, 
with  ink. 

3.  Interlineations  and  erasures  are  to  be  avoided  when  pos- 
sible ;  but  when  they  are  unavoidable,  either  in  the  specifications, 
the  contract,  or  the  bond,  they  should  be  noted,  word  by  word, 
immediately  above  the  signatures  of  the  witnesses,   specifying 
the  number  of  each  line  where  they  occur;  and  certificate  should 
be  made  that  each  specific  correction  or  alteration  was  made 
before    the    contract    was    signed.      A    general    statement    that 
"erasures  and  interlineations  were  made  before  execution"  is 
wholly  insufficient. 

4.  The  full  name  and  residence  of  each  signer  of  contract 
and  bond  should  be  stated  in  the  body  of  the  instrument  and 
the  signature  of  each  person  should  be  witnessed  by  two  other 
persons  who  should  state  their  places  of  residence. 

5.  When  firms  contract,  the  name  of  the  firm  and  the  full 
name  of  each  member  thereof  should  be  written  at  the  beginning 
of  the  contract;  for  instance,  "Smith,  Brown  &  Co.,  of  the  City 
of  New  York,  a  firm,  composed  of  John  S.  Smith,  Charles  B. 
Brown,  and  John  W.  Robinson".    The  contract  should  be  signed 
in  the  firm  name,  viz:   "Smith,  Brown  &  Co.,  by  John  S.  Smith". 
The  bond  given  to  guarantee  fulfillment  of  a  firm  contract  should 
be  in  the  name  of  the  individuals  composing  the  firm  and  should 
be  signed  and  sealed  by  each  of  them,  or  by  his  duly  authorized 
attorney,  proof  of  whose  authority  must  be  attached. 

6.  When  an  incorporated  company  enters  into  contract,  the 
corporate  name  of  the  company  should  be  written  at  the  begin- 
ning .of  the  contract  and  bond;  for  instance,  "The  Smith  and 
Brown  Dredging  Company,  a  corporation  created  by  and  existing 
under  the  laws  of  the  State  of  New  York,  and  having  its  prin- 
cipal office  in  the  City  of  New  York,  in  said  State".    The  contract 
and  bond  should  then  be  signed  with  the  corporate  name,  by  a 
person  duly  authorized  to  do  so,  sealed  with  the  corporate  seal, 
and  a  certificate,  showing  the  signer's  authority  to  sign  sealed 
instruments  in  its  behalf  and  that  the  seal  affixed  is  the  corporate 
seal,  should  be  made  by  the  secretary  of  the  corporation  or  other 
custodian  of  its  records,  in  the  form  prescribed.    In  cases  where 


378 


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CIVIL  SPECIFICATIONS  AND  CONTRACTS        159 

a  corporation  or  other  body  organized  under  law,  has  no  seal, 
one  must  be  adopted  for  the  occasion,  and  proof  thereof  should  be 
made  by  affidavit  of  the  secretary. 

7.  The  date  of  the  bond  must  not  antedate  that  of  the  con- 
tract. 

8.  A  firm  will  not  be  accepted  as  surety,  nor  will  a  partner 
be  accepted  as  a  surety  for  a  copartner,  or  for  a  firm  of  which 
he  is  a  member.    An  officer  of  a  corporation  will  not  be  accepted 
as  surety  for  such  corporation.    In  no  case  will  a  married  woman 
or  an  infant  be  accepted  as  a  surety,  and  when  an  unmarried 
woman   (widow  or  spinster)  is  given  as  a  surety,  she  must  be 
described  as  such  in  the  body  of  the  bond;  nor  will  a  bonded 
officer  of  the  United  States  be  accepted  as  a  surety ;  nor  will  any 
person  be  accepted  who  is  an  official  or  employe  of  any  branch 
of  the  public  service  having  to  do  with  the  contract,  performance 
of  which  is  guaranteed  by  the  bond. 

9.  There  must  not  be  less  than  two  individual  sureties,  but 
one  corporate  surety,  duly  qualified  under  the  act  of  Congress  of 
August  13,  1894,  may  be  accepted  as  sole  surety,  provided  it  files 
or  has  filed  with  the  Solicitor  of  the  Department  of  Commerce 
and  Labor  full  proof  of  such  compliance  with  the  act  as  qualifies 
it  to  act  as  surety  in  the  case.    The  Contractor  and  sureties  should 
sign  (or  execute)  each  bond.    Each  surety,  including  a  corporate 
surety,  must  qualify  in  double  the  amount  of  the  bond.     Indi- 
vidual sureties  must  justify  upon  the  form  of  "Bondsman's  Oath" 
prescribed,  and  corporate  surety  companies  upon  the  form  of 
"Justification  by  Corporate  Surety". 

10.  The  affidavits  or  affirmations  of  sureties  must  be  made 
before  an  officer  authorized  to  administer  oaths  generally.    The 
authority  to  administer  such  oath  must  be  shown  by  certificate, 
unless  the  oath  was  taken  before  a  judge  of  a  court  of  record,  or 
before  a  clerk  or  deputy  clerk  of  a  court  of  record,  a  United 
States  commissioner,  or  a  notary  public,  and  the  official  seal  is 
attached.     There  should  be  a  separate  and  distinct  impression 
of  the  official  seal  for  each  oath  or  affirmation.    The  official  title 
should  follow  the  signature. 

11.  Except  in  the  case  of  proper  corporate  sureties,  a  judge 
or  clerk  of  a  state  court  of  record,  a  judge  or  clerk  or  deputy 
clerk  of  a  United  States  Court,  a  United  States  district  attorney 
or  one  of  his  assistants,  a  United  States  commissioner,  or  a  post- 
master must  certify  that  the  sureties  are  sufficient  to  pay  double 
the  penalty  of  the  bond. 

12.  An  adhesive  seal  should  be  affixed  to  the  signature  of 
each  principal  and  surety  upon  the  bond,  except  when  the  prin- 


379 


160         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

cipal  or  surety  is  a  corporation,  in  which  case  the  corporate  seal 
should  be  affixed. 

13.  When  contracts  and  bonds  have  been  thus  prepared,  and 
signed  and  sealed  by  the  officer  making  them  in  behalf  of  the 
United  States,  they  should  be  forwarded  to  the  Board  for  its 
approval  and  the  approval  of  the  Secretary  of  Commerce  and 
Labor. 

14.  When  approved  by  the  Board  and  by  the  Secretary  of 
Commerce  and  Labor,  one  copy  shall  be  returned  to  the  officer 
making  the  contract,  for  delivery  to  the  Contractor. 


PROPOSALS 

Proposals  or  bids  are  offers  or  tenders  to  do  a  certain  thing 
or  to  perform  certain  work,  on  certain  conditions,  for  a  con- 
sideration. They  are  generally  in  writing. 

The  Engineer  should  prepare  a  blank  form  of  proposal  for 
the  bidders  to  use  in  making  the  tender,  with  the  necessary 
instructions  as  to  the  manner  in  which  it  is  to  be  filled  out,  the 
limit  of  time  when  bids  will  be  received,  etc. 

Notice  to  Bidders.  The  notice  or  instructions  to  bidders 
should  give  the  necessary  information  and  instructions,  and  should 
cover  the  following: 

The  form  in  which  the  bids  should  be  sent. 

The  party  for  whom  the  work  is  to  be  done. 

That  the  Contractor  be  skilled  and  regularly  engaged  in  the 
line  of  work  bid  for. 

When  and  where  the  plans  and  specifications  can  be  obtained. 

What,  if  any,  deposit  must  be  made  with  the  Company  before 
taking  out  a  set  of  the  plans  and  specifications. 

How  to  endorse  the  proposal. 

The  date  and  hour  when  the  reception  of  bids  will  be  closed. 

Bidder  to  visit  the  site  of  the  work. 

Bidder  to  examine  the  plans  carefully. 

Bidder  to  give  the  number  of  days  required  to  do  the  work 
and  date  of  completion. 

Bidder  to  follow  the  printed  form. 

Bidder  to  make  no  conditional  bid. 


380 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         161 

Bidder  to  write  amounts  as  well  as  to  give  figures  in  filling 
out  proposal. 

Bidder  to  furnish  guarantee  to  enter  into  contract  within 
days  of  award  of  contract. 

The  amount  of  the  one  or  more  bids  required  (if  any)  arid 
their  character. 

The  Company's  right  to  reject  any  or  all  bids,  or  to  accept 
any  bid. 

The  relation  between  the  Company  and  the  successful  bidder 
during  the  period  between  the  acceptance  of  bid  and  the  execu- 
tion of  the  contract. 

That  a  foreign  corporation  (one  chartered  in  another  State 
than  that  in  which  the  proposal  is  to  be  tendered)  must  furnish, 
with  its  proposal,  a  certificate  from  the  state  authorities  entitling 
it  to  do  business  within  said  State. 

That  the  proposals  must  contain  no  omissions,  erasures,  alter- 
ations, additions  not  called  for,  nor  conditional  bids. 

In  addition  to  the  above,  the  notice  should  call  the  bidder's 
attention  to  local  laws  affecting  the  employment  of  labor  and 
the  necessity  of  signing  the  proposal  with  the  individual's  name 
and  place  of  residence,  as  well  as  the  firm's  name  and  business 
address. 

If  quantities  are  set  forth  in  the  notice,  a  clause  should  state 
that  the  quantities  used  are  necessarily  approximate,  and  that 
the  Company  reserves  the  right  to  increase  or  decrease  them. 
The  purpose  of  sometimes  placing  the  approximate  quantities 
in  the  notice  to  bidders  is  to  use  them  as  a  basis  of  comparison 
to  determine  the  lowest  bidder,  in  unit  price  contracts. 

INSTRUCTIONS  TO  BIDDERS* 

U.  S.  Government  Lighthouse  Board.  The  following  instruc- 
tions to  bidders  are  used  by  the  United  States  Government  in 
the  proposals  of  the  Lighthouse  Board.  A  study  of  them  will 
give  much  information  on  the  subject. 

(1)  All  bids  and  guaranties  must  be  made  in  duplicate  upon 
the  printed  form  attached  hereto,  which  must  not  be  detached. 

*  Failure  to  comply  with  these  instructions  renders  the  bid  Informal  and  liable 
to  be  rejected. 


381 


162         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

(2)  Each  bid  must  state  in  words,  as  well  as  in  figures,  the 
sum  for  which  the  entire  work,  as  shown  on  the  plans  and 
described  in  the  specifications,  will  be  completed  and  delivered 
at  such  time  as  is  named  in  the  specifications. 

•  (3)  The  work  will  be  subject  to  the  personal  supervision  of 
the  Lighthouse  Engineer  or  his  agent,  and  all  facilities  must  be 
afforded  him  for  inspecting  the  materials  and  workmanship. 

(4)  All  blanks  in  the  form  of  bid  or  guaranty  must  be  filled 
in.    Interlineations  and  erasures  in  the  bid  and  guaranty  are  to 
be  avoided,  but  when  they  are  unavoidable  they  should  be  specifi- 
cally noted  word  by  word  by  the  signers  as  having  been  made 
before   execution.     The   general  statement   that  "erasures   and 
interlineations  were  made  before  execution"  is  insufficient. 

(5)  No  bid  will  be  received  by  telegraph. 

(6)  The  bidder's  place  of  residence,  with  county  and  State, 
must  be   given  after  his  signature,  which  must  be  written  in 
full. 

(7)  Anyone  signing  a  bid  as  the   agent  of  another,   or   of 
others,  must  file  with  it  legal  evidence  of  his  authority  to  do  so. 

(8)  When  firms  bid,  the  name  of  the  firm  and  the  full  name 
of  each  member  thereof  should  be  written  at  the  beginning  of 
the  bid;  for  instance,  "Smith,  Brown  &  Co.,  of  the  City  of  New 
York,  a  firm  composed  of  John  S.  Smith,  Charles  B.  Brown,  and 
John  W.  Robinson".    The  bid  should  be  signed  in  the  firm  name 
by  a  member  of  the  firm,  thus,  "Smith,  Brown  &  Co.,  by  John  S. 
Smith,  a  member  of  the  firm".     When  corporations  bid,  the  bid 
should  be  signed  with  the  corporate  name  by  some  person  duly 
authorized  to   do   so    (evidence   of  whose   authority  should  be 
appended),  and  sealed  with  the  corporate  seal. 

(9)  Bidders  should  satisfy  the  United  States  of  their  ability 
to  furnish  the  materialand  perform  the  work  specified.    Lack  of 
evidence  of  such  ability  will  be  sufficient  cause  for  rejection  of 
any  bid. 

(10)  Reasonable   grounds  for  inferring  that   any  bidder  is 
interested  in  more  than  one  bid  for  the  same  item  will  cause  the 
rejection  of  all  bids  in  which  he  is  interested. 

(11)  Bids'  submitted  by  different  members  of  the  same  firm 
or  copartnership  will  not  be  considered. 

(12)  The  right  is  reserved  to  reject  any  or  all  bids  or  any 
part  of  a  bid,  to  strike  out  any  item  or  items  in  the  specifications, 
and  to  waive  any  defects. 

(13)  All  bids  must  be  signed  and  inclosed  in  an  envelope 
indorsed  "Proposals  for  the  construction  of  buildings  at  Punta 
Gorda  Light  Station,  Calif or^a",  and  then  inclosed  in  another 
envelope  and  either  delivered  in  person  to  the  office  of  the  Engi- 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         163 

neer  of  the  Twelfth  Lighthouse  District  at  San  Francisco,  Cal., 
or  addressed  and  sent  to  him  through  the  mail,  postage  prepaid. 

(14)  All  bids  will  be  publicly  opened  and  recorded  at  the  time 
specified  in  the  advertisement.    Bidders  are  invited  to  be  present 
and  to  witness  the  opening  of  the  bids. 

(15)  The  contract  will  be  in  the  form  attached  hereto,  and 
bidders  are  understood  as  accepting  the  terms  and  conditions 
contained  in  such  form  of  contract. 

(16)  The  accompanying  advertisement,  plans,  and  specifica- 
tions, together  with  these  instructions,  will  form  a  part  of  the 
contract. 

(17)  Should  the  bidder  to  whom  the  contract  may  be  awarded 
fail  to  enter  into  contract  within  10  days  after  notice  is  given 
him  that  his  bid  has  been  accepted,   he  will  be  considered  a 
defaulting  bidder,  and  recommendation  will  be  made  to  the  Sec- 
retary of  Commerce  and  Labor  that  thereafter  no  proposal  of  his 
be  considered. 

(18)  A  bond,  with  one  corporate  surety  or  two  individual 
sureties,  in  the  sum  of  25  per  cent  of  the  amount  of  the  bid,  will 
be  required  for  the  faithful  performance  of  the  contract,  condi- 
tioned also  that  the  Contractor  shall  promptly  make  payment  to 
all  persons  supplying  him  or  them  with  labor  or  materials  in  the 
prosecution  of  the  work  provided  for  in  such  contract.     Each 
surety  will  be  required  to  justify  in  double  the  amount  of  the 
bond.     If  at  any  time  during  the  contract  period  the  Secretary 
of  Commerce  and  Labor  deems  the  security  furnished  by  the  Con- 
tractor insufficient,  additional  security  may  be  required. 

(19)  A  firm  will  not  be  accepted  as  a  surety  or  guarantor, 
nor  will  a  partner  be  accepted  as  a  surety  or  guarantor,  for  a  co- 
partner or  for  a  firm  of  which  he  is  a  member.    An  officer  of  a 
corporation  will  not  be  accepted  as  a  surety  or  guarantor  for 
such  corporation.     A  married  woman  or  an  infant  will  not  be 
accepted  as  a  surety  or  guarantor  under  any  circumstances. 

(20)  No  bid  will  be  accepted  or  contract  entered  into  until 
approved  by  the  Lighthouse  Board  and  the  Secretary  of  Com- 
merce and  Labor. 

(21)  Transfers  of  contracts,  or  of  interests  In  contracts,  are 
prohibited  by  law.     (See  U.  S.  R.  S.,  sec.  3737.) 

(22)  Payment  for  the  work  will  be  made  upon  the  certificate 
of  the  agent  of  the  Lighthouse  Board  that  it  has  been  completed 
and  delivered  according  to  contract. 

(23)  The  entire  work  must  be  completed  and  delivered  at  the 
time  provided  for  in  the  specifications  and  contract. 

(24)  Any  expense  incurred  by  the  United  States  on  account 
of  failure  on  the  part  of  the  Contractor  to  perform  the  service 


164         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

for  which  he  has  entered  into  contract  will  be  sufficient  to  cause 
the  annulment  of  the  contract,  should  the  Lighthouse  Board,  with 
the  approval  of  the  Secretary  of  Commerce  and  Labor,  so  decide. 

(25)  No  proposal  will  be  considered  unless  accompanied  by  a 
guaranty  or  a  certified  check  in  manner  and  form  as  directed  in 
these  instructions. 

(26)  The  guaranty  attached  to  each  copy  of  the  bid  must  be 
signed  by  two  responsible  guarantors,  to  be  certified  as  good  and 
sufficient  guarantors  by  a  judge  or  clerk  of  a  United  States  court, 
a  United  States  district  attorney  or  one  of  his  assistants,  a  United 
States  commissioner,  a  postmaster,  or  a  judge  or  clerk  of  a  state 
court  of  record,  with  the  seal  of  said  court  attached,  or  by  a 
guaranty  or  surety  company  duly  authorized  in  accordance  with 
the  provisions  of  an  Act  of  Congress  approved  August  13,  1894. 

(27)  Each  guarantor  must  justify  in  the  sum  of  20  per  cent 
of  the  amount  of  the  bid.     The  liability  of  the  guarantors  and 
bidder  is  expressed  in  the  guaranty  attached  to  the  bid. 

(28)  Plans  and  specifications  must  accompany  bid. 

(29)  No  person  who  has  failed  to  perform  satisfactorily  any 
contract  with  the  United  States  or  to  abide  by  any  bond  or 
guaranty  given  by  him  for  the  performance  of  any  contract  or 
proposal  will  be  accepted  as  guarantor. 

(30)  In  lieu  of  the  guaranty  a  certified  check  in  a  sum  equal 
to  one-fourth  of  the  amount  of  the  bid,  payable  to  the  order  of  the 
Secretary  of  Commerce  and  Labor,  will  be  accepted,  and  the  pro- 
ceeds of  such  check  shall  become  the  property  of  the  United  States, 
if,  for  any  reason  whatsoever,  the  bidder,  after  the  opening  of  bids, 
withdraws  from  the  competition,  or  refuses  to  execute  the  con- 
tract and  bond  required  in  the   event  of  said  contract  being 
awarded  to  him.    All  checks  submitted  will  be  returned  to  the 
bidders  immediately  after  the  approval  of  the  contract  and  bond 
executed  by  the  successful  bidder. 

(31)  The   attention   of  intending  bidders   for   this  work   is 
invited  to  an  Act  of  Congress  approved  August  1,  1892,  which 
provides  that  the  service  and  employment  of  all  laborers  and 
mechanics  employed  by  any  contractor  or  subcontractor  upon 
any  of  the  public  works  of  the  United  States  or  of  the  District  of 
Columbia  is  limited  and  restricted  to  8  hours  in  any  1  calendar 
day,  and  that  it  shall  be  unlawful  for  any  such  contractor  or  sub- 
contractor whose  duty  it  shall  be  to  employ,  direct,  or  control 
the  services  of  such  laborers  or  mechanics  to  require  or  permit 
any  such  laborers  or  mechanics  to  work  more  than  8  hours  in 
any  calendar  day,  except  in  case  of  extraordinary  emergency. 
A  violation  of  this  statute  is  punishable  by  a  fine  or  imprison- 
ment, or  by  both  fine  and  imprisonment. 


384 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         165 

Provisions  for  Recording  Prices.  The  notice  to  bidders  should 
be  attached  to  the  form  of  proposal  and  form  a  part  of  the  con- 
tract. In  the  form  of  proposal  it  is  well  to  have  under  the  head 
of  Price  Bid,  two  columns;  one  headed  dollars,  the  other  cents, 
as  given  below : 


PRICE   BID 


"Wrought  iron,  per  pound,  ...................  .?.?.  ....................... 

dollars  .............  three  ...........  cents 

Concrete,   per   cubic   yard,  ..................  ?i.Ye.  ____________________ 

dollars  .....  sixty^fiye  ......  cents 

Bessemer    steel    rails,    per    ton,  .....  tw.e.ri.t.y-11.iM... 


dollars 


.?.?.„...     ......  cents 


The  greatest  number  of  mistakes  are  generally  made  by  bid- 
ders in  placing  the  decimal  point  in  the  wrong  position.  The 
above  suggested  form  helps  to  prevent  this.  Of  course  mistakes 
in  formal  bids  cannot  be  rectified  after  the  bid  has  been  opened, 
no  matter  how  apparent  the  error  may  be. 

The  following  cautionary  clause  is  sometimes  inserted  in  the 
form  of  proposal  : 

Caution  —  Bidders  are  cautioned  against  placing  a  dollar  bid 
in  the  cents  column,  and  the  reverse;  as  any  error  of  this  char- 
acter, no  matter  how  obviously  it  may  be  an  error,  will  cause  the 
rejection  of  the  whole  bid  as  being  informal. 

TYPICAL  PROPOSALS 

The  following  will  illustrate  the  wording  used  in  describing 
various  items  in  proposals. 

PROPOSAL  I 


(City,  County,  and  State)       (Date).  ---------  1*™**?.'  ...........  191......... 

To    the      Commissioner  of  Bridges,   City  of  Bergen,   State  of 

Wisconsin.  ,  ..................................................................................  _ 

gjr.  _  ..^....hereby  propose  to  furnish  all  materials,  appliances, 
labor,  and  transportation  necessary  to  perform  the  work,  and 
submit  to  all  conditions  as  represented,  intended,  and  implied, 
both  particularly  and  generally,  in  the  specifications  and  articles 


385 


166 


CIVIL  SPECIFICATIONS  AND  CONTRACTS 


of  agreement,  for  the 5522Eil£J£^L^lSlJ2IS£: 

Black  Creek, 

examined  at  the  office  of  .__J£^^ 

in  the  Ordinance  of  Councils,  for  the  construction  of  the  said  work, 
and  perform  all  additional  work  that  may  be  required,  upon  the 

following  terms,  to  wit: 

PRICE  BID 
Item  No    1.     For  all  excavations  of  all  classes  n 

.  .    ,  ,  .  ,        ,  „     DOLLARS    CENTS 

of    materials,    per    cubic    yard,    the    sum    of 

dollars _!*•.?*? cents  2      50 

Item  No.  2.    For  concrete,  Class  A  1-3-6,   per 

cubic  yard  in  place,  the  sum  of ®.ie.X.?.?. 

dollars .e.iJ?hty. cents  11      80 

Item  No.  3.     For  terra  cotta  sewer,  12  inches 

and  under  in  place  complete,  with  all  appurte- 
nances per  linear  foot,  the  sum  of *w° 

dollars *e.?. cents  2      10 

Item   No.   4.     For   vitrified-brick  pavement,   in 

place  per  square  foot,  the  sum  of .?.?. 

dollars .^.f..^.^. cents  0      30 

Item  No.  5.    For  reinforcing  steel,  in  place,  per 

pound,      the     sum     of ?.? dollars 

cents  0      05 

Item  No.   6.     For  placing  city  hydrants,   each 

the  sum  of .flfle.e..n. dollars tw.^y 

cents  15  j   20 


NOTE. — When  it  is  likely  that  some  additional  work  will  have  to  be  done 
by  force  account,  it  is  wise  to  have  the  bidder  quote  a  price  per  hour,  for  the 
various  classes  of  additional  labor  and  use  of  machinery,  the  items  appearing 
in  the  proposal  as  follows: 

Additional  Work.  For  additional  labor  and  use  of  machinery 
of  the  various  classes  enumerated  below,  as  ordered  by  the  Chief 
Engineer,  including  cost  of  superintendence,  use  of  tools,  repairs, 
oil,  waste,  and  fuel. 

Item  No.   7.     For  foreman,   per  hour,  the  sum 

of .?.?. dollars....?.e.ye.n.ty/lf.y.e. 

cents 
Item  No.  8.     For  riveter,  regular  working  hours, 

per  hour,   the   sum   of. £.?. dollars 

......sixty cents 


PRICE  BID 


75 


60 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         167 


Item  No.  9.  For  riveter,  overtime,  per  hour,  the 

sum  of .?.?. .dollars ninety 

cents 

Item  No.  10.  For  use  of  team  (2  horses  and 
wagon),  including  driver,  per  hour,  the  sum 
of .n.°. dollars seventy centg 

Item  No.  11.  For  use  of  boiler  and  hoisting 

engine,  per  hour,  the  sum  of n.9 

dollars .seyenty-five cents 

Item  No.  12.  To  be  added  to  all  additional  ma- 
terials specially  purchased  by  the  Contractor 
by  written  order .t.e.n. per  cent 


PRICE    BID 


DOLLARS 

CENTS 

0 

90 

0 

70 

0 

75 

?.e. agree  to  complete  the  whole  of  the  work  in 

1?P...... working  days  from  the  date  of  notice  from  the 

Chief  Engineer  to  proceed. 

WITNESS .°.ll.r. hand,  this 15th day  of 

January ,  . 

^^  u... _ 

Trading  as  SMITH,   JONES  &  BROWN,   Contractors. 
NOTE. — The  Contractor  shall  here  give  individual  as  well  as  firm  names. 

Address  ^  ?out-11  ^°^ 

The  following  is  a  form  of  guaranty  for  the  bidder  executing 
contract  within  10  days  of  the  notice  that  his  bid  has  been  ac- 
cepted. It  should  be  attached  to  the  proposal,  as  a  part  thereof. 


T, 


of 


GUARANTY 

Standard   Construction   Company  ............................. 

-  .......  a   Corporation  exist- 


- _ 
ing  underheawsof  the  State  of  ............  N?F..^         -hereby 

hundred 


i        i       ^  *  -f  ^    V.-A  nf          ten  thousand  five  hundred 
undertakes  that  if  the  bid  ot  .................  .....  ..................  •--"  ...... 

dollars    herewith  accompanying,  dated  ...............  a™a.r.y     .„•    . 

191  7'1/for..  ^he..  construction   of  the.  Little..Falls  bridge  on 
the  line'  of  the  Ontario  Central  Railroad  ,  ................................. 


387 


168         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

be  accepted  as  to  any  or  all  of  the  items  bid  for,  the  said  bidder 
Standard  Construction  ^Company 

will,  within  ten  (10)  days  after  notice  of  award  of  contract,  enter 
into  a  contract  with  the.....  ............  ta^o_Central_  Railroad  .....  __  ....... 

Company,  to  perform  all  work  specified  therein  at  the  prices 
offered  by  said  bid,  and  will  give  bond  with  good  and  sufficient 
surety  or  sureties,  as  may  be  required,  for  the  faithful  and  proper 
fulfillment  of  such  contract.  And  said  Corporation  binds  itself  and 
its  successors  to  pay  the  ...............  0?.la.r.49...Ce£t£.a.L..?ailL0M  .............. 

Company,  in  case  the  said  bidder  shall  fail  to  enter  into  such  con- 
tract or  give  such  bond  within  ten  (10)  days  after  said  notice  of 
award  of  contract,  the  difference  in  money  between  the  amount 
of  bid  of  said  bidder  on  the  work  so  accepted,  and  the  amount 
for  which  the  ________________  Ontario  Central  ...Railroad  ..................  Company 

may  contract  with  another  party  to  perform  said  work,  if  the 
latter  amount  be  in  excess  of  the  former. 

IN  WITNESS  WHEREOF,  The  name  and  corporate  seal  of 
said   corporation   has   been   hereto    affixed,   this  .............  -^^  ............. 

day   of  .............  Ja?uary.?  .................  191.  A  ......  ,    and   these    presents    duly 

signed  by  its  (1)  .........  .??.e.?Ad.?.!}.!:.'.  ..............  pursuant  to  a  resolution  of 

its  (2)  __________  *°*rA.°LPi™9t?.r..s..>  ................  passed  on  the 

day  of  .......  January.'  .........  A.  D.  191.  J.  ....... 

Attest:     [CORPORATE  SEAL]     (3) 


By 

Secretary  President 

(1)  The  president  or  officer  authorized  to  sign  for  the  Corporation. 

(2)  The  board  of  directors  or  other  governing  body  of  the  Corporation. 

(3)  Here  affix  the  corporate  seal. 

NOTE,  ^nstead  of  a  guaranty  of  the  above  nature,  sometimes  a  certified 
check,  drawn  on  a  national  bank  or  trust  company,  is  required  to  accompany  the 
proposal  to  serve  the  same  purpose. 

PROPOSAL  II 

The  following  form  of  proposal  may  be  used  in  railroad  work  : 
For  the  grading  and  structures  on  the  ...............  _?^£aA?.hJr  ............. 

.....  Line.  ..........  Railroad  from   Station  .............  ?®?.  ................  to   Station 

..........  P?e.hundr_ed__8ixteen  ........  the  undersigned  hereby  certif  A63  ..... 

that  .............  he  .....  __  ha?  ........  sufficiently  examined  the  locality  and  sec- 

tions of  the  ............  ?lrai^t  _Line  ..........  Railroad  on  which  the  work 


388 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         169 


proposed   for  below  is   situated;   and   that he ha.? 

also  carefully  examined  the  specifications,  terms,  and  conditions 
applicable  to  said  work,  set  forth  in  the  form  herewith  attached, 
and  having  made  such  examinations  and  understanding  thor- 
oughly the  nature  and  conditions  of  the  work  to  be  let,  the  under- 
signed hereby  proposes  to  the ftral^yyUMjtoilTOftd 

Company  to  do  all  the  work  on  either  or  all  of  the  items  to  which 
prices  are  affixed  in  the  following  schedule,  according  to  speci- 
fications, terms,  and  conditions  aforesaid;  and  on  the  accept- 
ance of  these  proposals  for  all  or  either  of  the  items  named 
therein,  do.6.? hereby  bind !?A?.??i? to  enter  into  and  exe- 
cute the  work  thereon,  at  the  following  prices,  viz : 


Grading 

(1)  Clearing,  per  acre,  the  sum 
of 

(2)  Grubbing,  per  acre,  the  sum 
of 

(3)  Solid  rock,  per  cubic  yard, 
the  sum  of 

(4)  Loose  rock,  per  cubic  yard, 
the  sum  of 

(5)  Earth    in    cuts,    per    cubic 
yard,  the  sum  of 

(6)  Earth  borrowed,    per   cubic 
yard,  the  sum  of 

(7)  Ditching  in  earth,  per  cubic 
yard,  the  sum  of 

Excavations    in    Water    for    Bridge 
Foundations 

(8)  Solid  rock,  per  cubic  yard, 
in  water  for  bridge  founda- 
tions, the  sum  of 

(9)  Loose  rock,  per  cubic  yard, 
in  water  for  bridge  founda- 
tions, the  sum  of 

(10)  Earth,    per    cubic    yard,    in 
water    for    bridge    founda- 
tions, the  sum  of 

Masonry 

(11)  First-class     masonry,     per 
cubic    yard    in    place,    the 
sum  of 


SECTION  1 


SECTION  2 


DOLLARS 

CENTS 

DOLLARS 

CENTS 

50 

00 

65 

00 

245 

00 

280 

00 

1 

50 

1 

00 

0 

62 

0 

68 

0 

30 

0 

32 

0 

30 

0 

32 

0 

22 

0 

25 

3 

00 

2 

55 

1 

45 

1 

45 

1 

20 

1 

30 

8 

00 

8 

00 

170         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Masonry — Cont'd  SECTION  1  SECTION  2 

(12)  Second-class    masonry, 
cubic    yard    in    place, 
sum  of 

(13)  Third-class     masonry, 
cubic    yard    in    place, 
sum  of 

(14)  Slope  wall,  per  cubic  yard, 
in  place,  the  sum  of 

(15)  Rip-rap,  per  cubic  yard  in 
place,  the  sum  of 

(16)  Concrete    No.    1,    per 
yard  in  place,  the  sum  of 

(17)  Concrete   No.    2,    per 
yard  in  place,  the  sum  of 

(18)  Concrete   No.    3,    per 
yard  in  place,  the  sum  of 

Frame  and  Pile  Trestle 

(19)  Framing   and   erecting   pile 
and  timber  trestles,  per 
feet  board  measure  with  all 
appurtenances  in  place,  the 
sum  of 

(20)  Pointing,    shoeing,    drr 
and    sawing    off    piles, 
linear   foot   measured   : 
"cut-off"  to  point,  the  sum 
of 

Timber  in  Foundation 

(21)  Yellow  pine  in  private  cross- 
ings,   over   meadow   dit< 
and  box  drains,  per  M 
board  measure  with  all 
purtenances    in    place, 
sum  of 

(22)  Hauling  and  laying  12-inch 
double  strength  terra  cotta 
sewer  pipe,  per  lineal  foot  in 
place,  the  sum  of 

(23)  Hauling  and  laying  18-inch 
double  strength  terra  cotta 
pipe,  per  lineal  foot  in  place, 
the  sum  of 


per 
the 

DOLLARS 

CKNTS 

DOLLARS 

CENTS 

6 

50 

6 

50 

per 

the 

rQ-w*rl 

4 

00 

4 

00 

ciL  '  1  . 

2 

50 

2 

50 

d  in 

ubic 

2 

00 

2 

00 

>f 
ubic 

11 

00 

11 

00 

f 
ubic 

7 

50 

7 

50 

f 

5 

75 

5 

75 

pile 
r  M 

i  all 

the 

^ing 

55 

00 

57 

00 

per 

'rom 

sum 

0 

13 

0 

14 

ross- 
ches 
feet 

ap- 

the 

inch 

42 

00 

42 

00 

otta 
)t  in 

inch 

0 

14 

0 

16 

otta 
ace, 

0 

28 

0 

28 

390 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         171 


Timber  in  Foundation — Cont'd 

(24)  Hauling  and  laying  24-inch 
double  strength  terra  cotta 
pipe,  per  lineal  foot  in  place, 
the  sum  of 

(25)  Hauling  and  laying  30-inch 
double  strength  terra  cotta 
pipe,  per  lineal  foot  in  place, 
the  sum  of 

(26)  Hauling  and  laying  12-inch 
cast-iron    water    pipe,     per 
lineal  foot  in  place,  the  sum 
of 

(27)  Hauling  and  laying  14-inch 
cast-iron     water    pipe,     per 
lineal  foot  in  place,  the  sum 
of 

(28)  Hauling  and  laying  24-inch 
cast-iron    water    pipe,     per 
lineal  foot  in  place,  the  sum 
of 


SECTION  1 


SECTION  2 


DOLLARS 

CENTS 

DOLLARS 

CENTS 

0 

52 

0 

52 

0 

80 

0 

80 

0 

16 

0 

20 

0 

20 

0 

22 

0 

40 

0 

44 

The  undersigned  further  propose     s     to  commence  work  on 

such  section  or  sections  as  may  be  awarded  to ?A? 

within thirty days  from  the  date  thereof,  and  to  complete 

the  same  on  QT  before  the 10th day  Of _July , 191. .$.:_ 


Signed  this 

Proposer's     residence 
Postoffice  Address    . 


day  of January, 191  4. 

805  Queen  Street, 
Lancaster, 

Pennsylvania. 


THE  ADVERTISEMENT 

Purpose.  The  advertisement  is  of  minor  importance  and  only 
in  government  and  some  municipal  contracts  is  it  considered  of 
sufficient  importance  to  be  made  a  part  of  the  contract. 

Under  the  law,  most  public  work  —  that  is,  government,  state, 
county,  municipal,  and  borough  work  —  must  be  advertised  in  a 


391 


172         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

certain  number  of  papers,  over  a  certain  period,  before  the  public 
letting  takes  place. 

The  Engineer  should  ascertain  the  requirements  of  the  law 
in  regard  to  advertising  public  work  before  drawing  up  a  con- 
tract, as  contracts  have  been  declared  invalid  upon  its  being  found 
that  they  had  not  been  properly  advertised. 

Of  course  the  object  of  advertising  is  to  secure  competition 
between  parties  who  are  engaged  in  the  kind  of  business  or  work 
to  be  performed,  and  hence  the  advertisement  should  be  so  headed 
as  to  attract  the  attention  of  the  firms  capable  of  performing  this 
work. 

Essential  Features.  The  advertisement  should  be  concisely 
worded,  as  every  word  is  an  additional  cost  to  the  party  for  whom 
the  work  is  to  be  done ;  on  the  other  hand,  it  should  give  the  fol- 
lowing information : 

(a)  A  heading  that  will  attract  the  attention  of  desirable 
bidders. 

(b)  The  address  where  plans  and  specifications  can  be  seen 
and  procured. 

(c)  The  address  where  proposals  will  be  received. 

(d)  The  date  of  the  insertion  of  the  advertisement. 

(e)  The  date  and  hour  until  which  proposals  will  be  received. 

(f )  The  manner  of  presenting  the  bid,  viz,  sealed,  or  in  dupli- 
cate or  triplicate,  etc. 

(g)  The  date  of  opening  the  bids. 

(h)  The  kind  and  approximate  quantity  of  work  to  be  done, 
or  such  information  as  will  give  an  idea  of  the  magnitude  of  the 
work. 

(i)  The  locality  where  the  work  is  to  be  done. 

(j)  The  right  to  reject  any  or  all  bids. 

(k)  The  name  and  address  of  the  parties  for  whom  the  work 
is  to  be  done,  or  their  Agent. 

Sometimes  the  entire  matter  included  in  the  "Notice  to  Bid- 
ders" under  "Proposals"  is  published.  The  objection  to  this  is 
the  great  cost  of  so  extended  an  advertisement. 

The  manner  of  arranging  these  requirements  will  be  shown  by 
a  few  examples. 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         173 
TYPICAL  ADVERTISEMENTS 
METAL  WORK 

To  Iron  Manufacturers,  (a) 

Office  of  the  Lighthouse  Engineer,  Third  District, 
Tompkinsville,  New  York   (b) 191 (c) 

Sealed  Proposals  in  duplicate   (d)   will  be  received  at  this 

office  (e)  until  12  o'clock  noon  (f) 

191 (g),  for  furnishing  the  materials  and  labor  of  all  kinds 

necessary  for  the  completion  and  delivery  of  the  metal  work  of 
the  Peck's  Ledge  Lighthouse  (h),  Cockenoe  Island  Harbor, 
Conn,  (i) 

Plans,  specifications,  forms  of  proposal,  and  other  informa- 
tion may  be  obtained  on  application  to  this  office  (b). 

The  right  is  reserved  to  reject  any  or  all  bids  and  to  waive 
any  defects,  (j) 
(k) 

Lieutenant  Col.  of  Engineers,  U.  S.  A.,  Lighthouse  Engineer. 

(a)  Heading,  (b)  Address,  (c)  Date  of  Insertion,  (d)  Manner  of  presenting, 
(e)  Proposals  received,  (f)  Bidding  closed,  (g)  Proposals  opened,  (h)  Character 
of  work,  (i)  Locality,  (j)  Right  to  reject,  (k)  Party  letting  work. 

BRIDGE  WORK 

The  following  is  an  advertisement  for  the  superstructure  of 
the  ill-fated  Quebec  bridge : 

The  clause  in  regard  to  prices  of  labor  is  unusual  in  an  adver- 
tisement. The  clause  in  regard  to  other  newspapers  inserting 
the  advertisement  without  authority  is  a  very  wise  one,  as  it  is 
not  an  unusual  practice  for  newspapers  in  municipalities  to  insert 
such  advertisement  without  orders  from  the  proper  party  to  do 
so,  and  then  issue  bills  for  same,  which  are  really  nothing  less 
than  blackmail. 

QUEBEC  BRIDGE 

DEPARTMENT  OP  RAILWAYS  AND  CANALS 
TENDERS  FOR  SUPERSTRUCTURE 

NOTICE  TO  CONTRACTOKS 

Sealed  tenders  addressed  to  the  undersigned  and  endorsed 
"Tender  for  Quebec  Bridge  Superstructure"  will  be  received  at 
this  office  until  12  o'clock  noon,  not  later  than  September  1,  1J 
for  the  superstructure  of  a  bridge  across  the  St.  Lawrence  River 
near  the  City  of  Quebec. 


393 


174         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Plans  and  specifications  may  be  seen  and  forms  of  tender 
obtained  on  and  after  July  1,  1910,  at  the  office  of  the  Quebec 
Bridge  Board  of  Engineers,  Canadian  Express  Building,  Montreal, 
and  at  the  Department  of  Railways  and  Canals,  Ottawa. 

Parties  tendering  will  be  required  to  accept  the  fair  wages 
schedule  prepared  or  to  be  prepared  by  the  Department  of  Labor, 
which  schedule  will  form  part  of  the  contract. 

Contractors  are  requested  to  bear  in  mind  that  tenders  will 
not  be  considered  unless  made  strictly  in  accordance  with  the 
printed  forms,  and  in  the  case  of  firms,  unless  there  are  attached 
the  actual  signatures,  the  nature  of  the  occupation,  and  place  of 
residence  of  each  member  of  the  firm. 

An  accepted  bank  check  for  the  sum  of  $500,000.00  made  pay- 
able to  the  order  of  the  Minister  of  Railways  and  Canals  of 
Canada  must  accompany  each  tender,  which  sum  will  be  forfeited 
if  the  party  tendering  declines  entering  into  contract  for  the 
work  at  the  rates  stated  in  the  offer  submitted  and  in  accordance 
with  the  terms  stated  in  the  form  of  contract  accompanying  the 
specifications. 

Checks  thus  sent  in  will  be  returned  to  the  respective  con- 
tractors whose  tenders  are  not  accepted. 

The  lowest  or  any  tender  not  necessarily  accepted. 

L.  K.  J., 

Secretary 

Department  of  Railways  and  Canals, 
Ottawa,  June  17,  1910. 

Newspapers  inserting  this  advertisement  without  authority  from  the  De- 
partment will  not  be  paid  for  it. 


MACADAM  EOADS 

Denison,  Texas. 

Sealed  proposals  will  be  received  by  the  Commissioners'  Court 
of  Grayson  County,  Texas,  up  to  the  hour  of  11  o'clock  A.M.,  on 
August  10,  1910,  at  the  office  of  said  Court  in  Sherman,  Texas, 
for  the  construction  of  approximately  65  miles  of  macadam  road- 
way in  Road  District  No.  1  of  Grayson  County,  Texas.  Said 
district  is  situated  in  the  north  central  part  of  Grayson  County, 
in  and  about  the  City  of  Denison. 

Profiles,  plans,  and  specifications  will  be  on  file  in  the  office 
of  J.  C.  Field,  Engineer  in  charge,  Denison,  Texas,  after  July  1, 
1910.  Copies  will  be  sent  applicants  on  receipt  of  $2.00,  to  be 
returned  to  depositor  if  bid  is  made.  A  certified  check  for 
$5,000.00  on  some  Grayson  County  bank  must  be  deposited  with 
each  bid,  to  be  returned  to  unsuccessful  bidders;  and  to  be 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         175 

returned  to  successful  bidder,  upon  his  entering  into  contract  and 
bond  in  accordance  with  his  bid,  within  10  days  from  its  accept- 
ance. Failure  so  to  enter  into  contract  and  bond  will  forfeit 
check  to  district. 

The  right  is  reserved  to  reject  "any  and  all  bids. 

H.  R.  W., 

Auditor,  Grayson  Co., 

Sherman,  Texas 

It  is  useless  to  multiply  examples  of  advertisements,  as  many 
examples  of  the  requirements  of  a  good  advertisement  can  be 
seen  at  any  time  in  the  leading  technical  journals. 

PRACTICE  IN  SPECIFICATION  AND  CONTRACT 
WRITING 

GENERAL  INSTRUCTIONS 

Examination  of  Actual  Work.  Below  will  be  found  a  few  sub- 
jects for  practice  in  specification  writing.  Before  attempting  to 
write  a  specification  for  any  of  the  subjects  given,  the  student,  if 
possible,  should  go  out  and  make  careful  examination  of  such  a 
piece  of  work  in  process  of  construction.  If  none  is  available, 
make  a  minute  examination  of  a  finished  structure,  note  its  strong 
points  and  its  defects,  and  seek  a  remedy  for  the  latter,  embodying 
the  ideas  in  the  specification  to  be  written. 

If  the  structure  is  in  process  of  building,  make  a  thorough 
examination  of  the  character  of  the  materials  entering  into  the 
work,  watch  the  process,  question  the  workmen  and  foremen  as 
to  character  of  foundation  and  as  to  any  special  features 
embodied  in  the  construction.  Examine  brands  of  materials  and 
if  better  processes  of  construction  are  apparent  to  you,  discuss  the 
subject  with  the  foreman  or  superintendent  with  the  idea  of 
getting  his  criticism  of  your  suggestions. 

Study  of  Good  Specifications.  Follow  this  up  by  collecting 
two  or  three  good  specifications  covering  the  subject  in  hand, 
and  make  a  comparative  study  of  them. 

Drawings.  If  drawings  are  to  be  a  part  of  the  contract,  the 
sheets  must  be  properly  numbered  and  a  list  of  them  set  forth  in 
the  specification,  which  list  should  be  inserted  just  before  the 
detailed  description  of  the  work. 


395 


176         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

Order  of  Headings.  A  complete  list  of  headings  and  subhead- 
ings should  be  made  and  arranged  in  their  proper  order.  This  is 
difficult,  as  there  are  so  many  items  which  have  little  connec- 
tion with  each  other. 

The  method  generally  followed  is  to  arrange  the  clauses  as 
nearly  as  possible  in  the  order  in  which  the  building  actually 
takes  place  in  the  work  under  consideration.  For  instance,  in  a 
railroad  specification  the  headings  should  be  arranged  as  follows : 
Clearing,  Grubbing,  Grading,  Tunnels,  Excavation,  Foundations, 
Masonry,  Pipe  Drains,  Timber  in  foundation,  Timber  in  trestles, 
Bridges,  Tracklaying,  Surfacing,  etc.  Of  course  there  are  many 
items  that  cannot  be  arranged  chronologically;  often  one  clause 
or  heading  suggests  the  following  one,  which  method,  carried  out 
consistently,  will  give  the  desired  result.  It  is  very  desirable 
that  specifications  for  a  complete  piece  of  construction  be  prop- 
erly indexed. 

The  following  examples  are  given  as  good  subjects  for  prac- 
tice in  specification  writing: 

TYPICAL  PROBLEMS 

Examples.  (1)  A  single-track  railroad  handling  heavy  freight 
traffic  wishes  to  replace  a  frame  trestle  across  a  stream  by  a  steel 
plate  girder  bridge  on  concrete  masonry  abutments;  clear  span 
75  feet.  The  approaches  to  the  bridge  back  of  the  abutments  are 
to  be  filled  in  with  material  obtained  by  widening  out  an  adjacent 
cut;  material  in  cut,  sand,  and  loose  rock;  borings  show  hard 
gravel  at  25  feet.  Prepare  a  complete  specification  for  both  sub- 
and  superstructure.  The  work  will  eventually  be  sublet;  the 
masonry  to  one  firm  and  the  steel  to  another,  and  the  grading 
and  foundations  to  still  another. 

The  work  is  located  in  Northern  New  York  State. 

(2)  A  timber  trestle  across  a  meadow  in  the  State  of  Wash- 
ington has  been  burned  and  must  be  replaced  at  once,  to  open 
traffic  at  the  earliest  possible  date.  The  trestle  is  1650  feet  long ; 
1100  feet  of  the  track  is  but  9  feet  above  the  marsh ;  the  550  feet 
remaining  varies  in  depth  from  9  to  22  feet;  profile  shows  but 
3  feet  of  earth  and  gravel  overlying  the  rock  at  the  lowest  point. 


396 


CIVIL  SPECIFICATIONS  AND  CONTRACTS         177 

Prepare  a  complete  specification  for  replacing  the  trestle  in  the 
most  economical  manner. 

(3)  Prepare  complete  specification  for  a  double-track  steel 
bridge ;  tracks  13  feet  center  to  center ;  span  245  feet ;  live  load, 
Cooper's  Class  E  50;  steel  to  be  erected  by  a  sub-contractor; 
bridge  to  be  complete ;  ties  laid  ready  for  the  rails ;  two  coats  of 
paint  after  erection. 

(4)  Prepare  a  complete  specification  for  a  concrete  retaining 
wall  875  feet  long,  varying  in  height  from  8  feet  above  track  at 
one  end  to  24  feet  at  the  other  end.    The  wall  is  surcharged  with 
a  sandy  loam  embankment,  15  feet  high  at  the  end  of  the  wall 
which  is  lowest,  2  feet  high  at  the  other.     Foundations  in  soft 
rock  in  Eastern  Pennsylvania. 

(5)  Write  a  complete  specification  and  articles  of  agreement 
for  the  building  of  a  double-track  electric  interurban  railroad 
22  miles  long,  in  Northern  New  Jersey.    The  road  crosses  2  nav- 
igable rivers — one  crossing  is  1700  feet  and  the  other  650  feet  in 
length.    Both  loose  and  solid  rock  will  be  encountered;  the  road 
crosses  under  2  trunk  line  railroads  and  over  4  others;  it  crosses 
at  grade  3  street  railways.     There  are  on  the  line  2  10-foot 
reinforced-concrete  arched  culverts;   1240  linear  feet  of  framed 
timber  trestle  on  concrete  footings.     Kail  70  pounds  per  yard. 
Track  in  stone  ballast.     To  be  operated  by  overhead  trolley. 
Electric  current  to  be  purchased  from  a  local  company.    Station 
grounds  to  be  graded. 

(6)  A  street  1  mile  long  is  to  be  paved  with  vitrified  brick 
on  concrete  base ;  streets  crossing  500  feet  apart ;  soil  sandy  loam. 
One  half  of  it  is  to  be  curbed  with  new  granite  curb.    The  other 
half  has  been  curbed  with  blue  stone  and  is  badly  out  of  line  and 
grade.     Water,  gas,  and  electric  conduits  are  in  the  street,  one- 
half  of  which  has  to  be  lowered  varying  in  depth  from  1  to  5  feet 
at  the  summit. 

Prepare  a  complete  specification  for  the  above,  bearing  in 
mind  that  each  company  owning  the  structures  in  the  street  will 
do  the  work  of  altering  its  pipe  and  conduits  at  the  expense  of 
the  Contractor. 

(7)  Prepare  complete  specification  for  a  curved  dam  to  be 
located  in  Georgia.     It  is  to  be  245  feet  long,  built  of  concrete 


397 


178         CIVIL  SPECIFICATIONS  AND  CONTRACTS 

faced  with  ashlar  masonry ;  soft  rock  foundations  with  the  abut- 
ting banks  of  the  river  of  same  material;  dam  will  be  18  feet 
high  above  river  bed  ;  maximum  depth  of  water  is  S  feet,  at  ordi- 
nary stages  ;  river  is  subject  to  frequent  freshets ;  purpose  of  dam 
is  for  flushing  out  at  frequent  intervals  a  large  main  sewer. 

(8)  Prepare  specification  for  two  docks  on  creosoted  piles; 
superstructure  to  be  of  reinforced  concrete;  depth  of  water  20 
feet,  to  be  dredged  to  32  feet  in  slip,  which  is  150  feet  wide; 
docks  each  to  be  65  feet  wide  and  450  feet  long;  concrete  bulk- 
head between  the  two  docks.    The  structure  will  be  located  at 
New  Orleans  and  will  have  two  docks,  the  upper  one  for  pas- 
senger service. 

(9)  Prepare  complete  contract  for  a  brick-arch  bridge;  span 
70  feet;  rise  12  feet;  springing  line  7  feet  above  the  sidewalks; 
bridge  carries  an  avenue  80  feet  wide  across  a  70-foot  street; 
there  is  on  the  street  a  double  track  electric  railway  on  which 
cars  are  very  frequent  and  travel  must  not  be  interfered  with; 
end  walls  and  parapet  to  be  of  first-class  masonry. 

(10)  A  Commission  of  the  Commonwealth  of  Massachusetts 
wishes  to  build,  in  the  City  of  Boston,  a  reinforced  concrete 
chimney,  10  feet  interior  diameter,  height  175  feet,  foundation  on 
hard  blue  clay. 

Prepare  complete  contract  for  same  including  Advertisement, 
Proposal,  with  Notice  to  Bidders,  and  form  of  Bond  required, 
Speeitieations,  and  Artieles  of  Agreement. 


REVIEW  QUESTIONS 


REVIEW  QUESTIONS 

ON  THE  SUBJECT  OF 

ESTIMATING 


1.  Estimate  the  weight  of  the  girder  shown  in  Fig.  120, 
Page  153,  Steel  Construction,  Part  II. 

2.  Estimate  the  weights  of  interior  floor  beams  in  Plate  G, 
Steel  Construction,  Part  IV.     Use  standard  connection  angles  for 
all  beams. 

3.  Estimate  the  weight  of  the  beams  in  Fig.  201  (a),  Steel 
Construction,  Part  IV. 

4.  Estimate  the  weight  of  the  columns  in  Fig.  205,  Steel 
Construction,  Part  IV,  allowing  a  unit  stress  of  12,000  pounds. 

5.  What  is  the  basis  of  estimating  for  structural  steel  work? 

6.  Give  in  your  own  words  your  idea  of  making  an  estimate 
of  steel  work. 

7.  What  would  you  consider  the  best  way   to    check   an 
estimate? 

8.  When  are  approximate  estimates  permissible,  and  how 
made? 

9.  Give  briefly  the  analysis  of  determining  cost  of  struc- 
tural steel  work. 

10.     What  are  the  elements  involved  in  estimating  cost  of 
fabrication? 


401 


REVIEW  QUESTIONS 

ON  THE  SUBJECT  OF 

STATICS 


1.  Define  concurrent  and  non-concurrent  forces,  equilibrant 
and  resultant. 

2.  What  do  you  understand  by  the  "Triangle  law"? 

3.  What  is  the  total  snow 'load  for  the  truss  if  the  snow 
weighs  20  pounds  per  square  foot  (horizontal)? 

4.  Compute  the  total  wind  load  for  the  truss  of  Question 
9,  when  the  wind  blows  75  miles  per  hour. 

5.  Make  a  complete  record  of  the  stresses  as  determined  in 
answer  to  the  preceding  question  for  cases  a,  6,  and  c,  and  for 
snow  load   as   computed  in  answer  to   Question   10.     Compute 
from  the  record  the  value. of  the  greatest  stress  which  can  come 
upon  each  member  due  to  combinations  of  loads,  assuming  that 
the  wind  and  snow  loads  will  not  act  at  the  same  time. 

6.  Find  the  magnitude  of  the  resultant  of  two  forces  mak- 
ing an  angle  of  70°  with  each  other,  one  being  30  pounds  and  the 
other  45  pounds. 

7.  The  lines  of  action  of  two  forces  of  65  and  35  pounds, 
respectively,  make  an  angle  of  120°.     Find  the  magnitude  of  the 
force  that  holds  them  in  equilibrium,  and  the  angles  that  it  makes 
with  each  given  force. 

8.  Draw  a  force  polygon  for  five  forces  in  equilibrium  and 
prove  that  any  diagonal  of  the  polygon  is  the  resultant  of  the 
forces  on  one  side  and  holds  in  equilibrium  those  on  the  other. 


402 


REVIEW  QUESTIONS 

ON  THE  SUBJECT  OF 

ROOF  TRUSSES 


1.  Name  and  describe  the  three  classes  of  roof  trusses, 
and  give  a  sketch  of  one  truss  of  each  class. 

2.  Give  a  sketch  of  the  Fink  truss  and  the  modified  Fink 
truss. 

3.  Given  W  =  i  al  (!+TQ)>  compute  the   dead  panel  load 

of  an  eight-panel  Fink  truss  of  80-foot  span,  if  the  distances  between 
trusses  is  20  feet  and  the  roof  covering  is  composed  of  corrugated 
steel. 

4.  Tell  how  a  felt  and  asphalt  roof  is  made  and  laid. 

5.  What  is  a  non-condensation  roofing? 

6.  Design  the  purlins  if  they  are  to  be  spaced  6  feet  apart 
and  the  trusses  are  to  be  spaced  16  feet  apart.     They  are  to  carry 
40  pounds  per  square  foot  of  roof  surface. 

7.  Write   one   page  on  the  economical  pitch  and  spacing 
of  roof  trusses. 

8.  If  the  trusses  are  of  80-foot  span  and  are  spaced  20  feet 
center  to  center,  and  are  eight-panel  Fink,  compute  the  stresses 
in  the  knee-braces  if  they  join  the  columns  8  feet  from  the  top. 
The  columns  are  25  feet  long;  the  normal  wind  pressure  on  the 
roof  is  12  pounds;  the  pitch  of  the  roof  is  £;  the  normal  wind 
pressure  on  the  side  of  the  building  is  25  pounds;  and  the  columns 
are  considered  free. 

9.  In  the  trusses  of  Question  8,  above,  compute  the  bending 
moment  in  the  posts. 

10.  If  in  Question  8,  above,  the  girts  are  placed  4  feet  apart, 
design  them. 

11.  If  a  post  is  25  feet  long,  has  a  total  direct  stress  of  20  000 
pounds  which  acts  at  the  center  of  the  column,  and  a  crane  load 
of  10  000  pounds  which  acts  12  inches  from  the  face  of  the  column, 
design  the  section  of  the  column  if  it  consists  of  four  angles  and 
a  plate. 


403 


ROOF  TRUSSES 

12.  A  compression  member  of  a  roof  truss  consists  of  two 
angles  placed  i  inch,  back  to  back,  and  has  a  stress  of  35  000 
pounds.     Design  the  member  if  it  is  6  feet  long. 

13.  If  the  member  of  Question  12,  above,  is  a  tension  member, 
design  it. 

14.  If  the  connection  plates  are  f  inch  thick,  determine  the 
number  of  f -inch  rivets  required  for  the  connections  of  the  member 
in  Question  12  above. 

15.  Make  a  sketch  showing  two  details  of  the  end  of  a  roof 
truss. 

16.  How  is  the  cost  of  structural  steel  determined? 

17.  If  the  maximum  wheel  reaction  is  19  000  pounds,  and 
the  wheel  base  is  9  feet,  design  the  runway  girder  if  the  trusses 
are  16  feet  apart. 

18.  If  the  maximum  wheel  reaction  is  40000  pounds,  and 
the  wheel  base  is  10  feet,  design  the  runway  girder  if  the  trusses 
are  16  feet  apart. 

19.  Determine  the  rivet  spacing  in  the  second  division  of 
the  runway  girder  of  Question  18,  above,  if  hg  is  30  inches. 

20.  Make  a  sketch  giving  two  gable  details,  and  state  the 
sizes  of  gutters  and  conductors. 

21.  State  the  different  classes  of  floors  employed  in  mill 
buildings,  and  give  a  sketch  of  two  classes. 


404 


REVIEW  QUESTIONS 

ON  THE  SUBJECT  OF 

CIVIL  ENGINEERING  SPECIFICATIONS 
AND  CONTRACTS 

PART  I 


1.  Describe  the  duties  and  responsibilities  of  the  engineer. 

2.  What  are  the  essential  features  of  detail  drawings? 

3.  What  is  the  purpose  of  specifications? 

4.  Define  General  Clauses,  Specific  Clauses. 

5.  Are  verbal  instructions  binding?     Why? 

6.  What  are  the  duties  of  an  inspector? 

7.  What  are  headers  and  stretchers? 

8.  Give  specifications  for  sand  to  be  used  in  grouting. 

9.  What  is  meant  by  Live  Load  and  Dead  Load? 

10.  What  are  Stress  Sheets  and  their  purpose? 

11.  Give  the  length  of  piles  generally  used  and  the  diameter 
at  both  ends  for  the  various  lengths. 

12.  Under  what  conditions  is  the  contractor  liable  for  loss 
of  grade  stakes. 

13.  What  are  the  duties  of  a  contractor? 

14.  What  provision  shall  a  contractor  make  to   enable  the 
inspection  of  his  work? 

15.  When  inspecting  shop  work  of  structural  steel  what 
defects  should  you  look  for? 

16.  As   engineer   what   would   you   consider    the   essential 
features  of  pile  driving? 

17.  What  defects  would  cause  you  to  reject  the  timber  to 
be  used  for  stringers  on  a  railroad  trestle? 

18.  What   are   the  essential   tests  for  structural   steel   for 
buildings? 


405 


REVIEW  QUESTIONS 

ON  THE  SUBJECT  OF 

CIVIL  ENGINEERING  SPECIFICATIONS 
AND  CONTRACTS 

PART  II 


1.  What  is  the  purpose  of  a  contract? 

2.  Make  up  a  form  of  general  agreement  to  cover  the  building 
of  a  house  in  your  town,  you  to  be  the  contractor.     Do  not  copy 
word  for  word  from  the  text,  but  try  to  cover  each  essential  clause. 

3.  Write  specifications  and  contract  to  cover  the  construction 
of  a  mill  building  (wood -construction)  in  your  town. 

4.  Make  up  an  advertisement  or  notice  to  contractor  that 
you  have  a  number  of  miles  of  road  to  construct  in  a  certain  locality. 

5.  Write  a  complete  specification  for  the  building  of  a  double- 
track  electric  interurban  railroad  25  miles   long  in  western  Con- 
necticut.    The  road  crosses  a  navigable  river  with  a  1500-foot 
crossing.     Both  loose  and  solid  rock  will  be  encountered;   the 
road  crosses  under  a  trunk  line  railroad  and  over  one  other;  it 
crosses  at  grade  two  street  railways:  there  are  on  the  line  two 
8-foot  reinforced-concrete  culverts,  box  type.      Rail  70  pounds 
per  yard.     Track  in  stone  ballast.     To  be  operated  by  overhead 
trolley.     Electric  current  to  be  purchased  from  a  local  company. 
Station  grounds  to  be  graded. 

6.  Prepare  specification  for  a  dock  on  creosoted  piles;  super- 
structure to  be  of  reinforced  concrete;  depth  of  water  15  feet, 
to  be  dredged  to  32  feet  in  slip  which  is  150  feet  wide;  dock  to  be 
65  feet  wide  and  450  feet  long.     The  structure  will  be  located 
in  Chicago  and  will  have  two  stories,  the  upper  one  for  passengers. 

7.  Prepare  a  notice  to  bidders  for  the  following:    A  Com- 
mission of  the  Commonwealth  of  Massachusetts  wishes  to  build 
in  the  city  of  Boston,  a  reinforced  concrete    chimney,   10  feet 
interior  diameter,  height  175  feet;  foundation  on  hard  blue  clay. 


406 


INDEX 


407 


INDEX 


The  page  numbers  of  this  volume  will  be  found  at  the  bottom  of  the  pages; 
the  numbers  at  the  top  refer  only  to  the  section. 


Page 
A 
Additional   men,   right   of   company 

to  employ  234 
Advertisements 

essential  features  392 

purpose  391 

typical  393 

bridge  work  393 

macadam  roads  394 

metal  work  393 

Quebec  bridge  393 

Agreement,  forms  of  356 

general  360 

railway  363 

Algebraic  composition 

of  concurrent  forces  52 

of  non-concurrent  forces  94 

Algebraic  conditions  of  equilibrium      62 

Alterations  244 

Apex  loads,  computation  of  66 

B 

Bond 
Borings 
Bridges 

highway 

railroad 

Buildings  for  engineer  and  inspector  239 
Buildings,  structural  steel  for 


Care  of  materials 

Cement 

Civil  specifications  and  contracts  221-398 

Claims 

Clauses   or   provisions,    general   and 

specific 

Components  and  resolution 
Concrete 
Note. — For  page  numbers  see  foot  of  pages. 


Concrete  macadam  320 

Concurrent  forces  48 

algebraic  composition  of  52 

in  equilibrium  59 

graphical  composition  of  49 

Conditions,  avoidance  of  unusual         227 

Contract  222,  351 

arbitrators  355 

bond  354 

consideration  353 

duties  of  parties  354 

essential  elements  351 

guaranty  354 

mutual  consent  353 

nature  and  purpose  351 

number  of  parties  351 

payment  clauses  355 

subject  matter  353 

Contract,  abandonment  or  violation  of  248 

Contract,  fulfilling  the  233 

execution  of  work  233 


249,  354 
234 

mspeuuuii  ui  WUIK. 
miscellaneous  obligations  of  con- 

&0i) 

tractor 

238 

291 

protective  and  labor  clauses 

237 

277 

Contractor 

ctor  239 

obligations  of 

238 

275 

duties  of 

233 

Contracts,  dividing  line  between 

228 

Couples 

96 

234 

Creosote,  treatment  of  timber  with 

301 

263 

Culverts 

273 

221-398 

cast-iron  pipe 

274 

243 

terra-cotta  drain  pipe 

273 

and 

Curbing 

327 

225 

D 

49 

Damages 

243 

264 

Dead  load  stress 

111 

409 


INDEX 


Page 

Definitions,  careful  statement  of  230 

Delays  238 

Drawings  223,  230 

general  231 

record  231 

Drawings,  plans,  etc.  230 

construing  230 

necessary  to  render  work  com- 
plete 231 
notes,  upon  drawings  232 
verbal  agreements  232 
work  in  accordance  with  plans      231 


Page 

Execution  of  work  (continued) 

borings  234 
care  of  materials  234 
delay  in  procuring  right  of  way  233 
duties  of  contractors  233 
extension  of  tune  235 
materials  to  be  furnished  234 
price  specifications  235 
prosecution  of  work  233 
right  of  company  to  employ  ad- 
ditional men  234 

Extra  work  244 


E 


Electrical  railway,  specifications  for 

overhead  construction  of  313 

Engineer  222 

knowledge  required  of  227 

Engineering  221 

Equilibrium 

algebraic  conditions  of  62 

condition  of,  defined  59 

graphical  condition  of  59 

Equilibrium  and  equilibrant  49 

Equilibrium  of  non-concurrent  forces     96 
determination  of  reactions  97 

Estimate,  monthly  247 

Estimating  11-43 

costs  34 

erection  41 

fabrication  38 

illustration  43 

paint  and  painting  39 

plain  material  35 

profit  43 

selling  costs  41 

shop  detail  drawings  38 

summary  43 

transportation  from  fabri- 
cating shop  to  building 
site  40 

transportation  from  mill  to 

shop  36 

structural  steel  for  buildings  11 

weights  15 

Execution  of  work  233 

Note. — For  page  numbers  see  foot  of  pages. 


Fink  truss,  complete  analysis  of  110 
Force 

algebraic    resolution,    into  two 

components  57 

components  and  resolution  49 

concurrent  48 

definition  of  45 

equilibrium  and  equilibrant  49 

graphic  representation  of  46 

graphical    resolution    into  two 

concurrent  components    56 

non-concurrent  49 

notation  47 

resultant  and  composition  49 

scales  47 

space  diagram  47 

Force  diagram  47 

Force  polygon  53 

Forces  in  tension  and    compression 

members  104 

Foundations  256 


G 


General  instructions 
contract 
drawings 
engineer 
engineering 
specifications 


221 
222 
223 
222 
221 
224 


Graphical      composition      of      non- 
concurrent  forces  91 
Graphical  condition  of  equilibrium  59 
Graphical  representation  of  a  force  46 


410 


INDEX 


Graphical  resolution  of  force  into 
two  concurrent  com- 
ponents 56 

Grouping  provisions  229 


Headings,  order  of 


II 


396 


Inspection  of  work  235 

cost  of  236 

during  construction  235 

final  inspection  236 

labor  furnished  to  inspector  236 

Insurance,  builders'  237 

Interference  with  travel  242 

Interstate     rules     for     classification 

and  inspection  of  yellow 

pine  lumber  272 

Iron  work  for  timber  trestles  304 


Page 

Mill  building  (continued) 

framing  190 

gable  details  216 

general  requirements  189 

knee-braces  198 

layout  189 

runway  girders  199 

types  of  buildings  188 

ventilators           ,  216 

Mistakes  in  plans  and  specifications     229 

N 

Non-concurrent  forces  49 

algebraic  composition  of  94 

equilibrium  of  96 

graphical  composition  of  91 

Notes  upon  drawings  232 

O 

Obligations  of  contractor  238 


Liability  of  contractor  241 

Liens  247 

Liquidated  damages  243 

Lumber  271 

classification  and  inspection  of 

yellow  pine  272 


M 


Marks  and  stakes  to  be  preserved        232 

Masonry  256 

classification  of  259-268 

waterproofing  268 

Materials  employed  227 

Measurements,  lines,  grades,  etc.          232 

lines  and  grades  by  engineer          232 

maiks  and  stakes  to  be  preserved  232 

quantity  estimates  232 

standard  of  measure  232 

work  to  conform  to  lines  232 

Mill  building  186-218 

.columns  193 

cornice  details  216 

definitions  and  description  186 

floors  218 

Note. — For  page  numbers  see  foot  of  pages. 


Pavements  322 

asphalt  329 
granite  block  paving  on  concrete 

base  325 
granite   block   paving   on    sand 

base  328 

telford  327 

vitrified-clay  brick  or  block  324 

wood  block  340 

Pavements,  sidewalk  344 

brick  345 
granolithic 

Payment  of  contractor  246 

Pile  shoes  256 

Pile  trestle  for  electric  railroad  296 

iron  work  304 

piling 

timber  and  framing  297 
Piles 

Piling,  specifications  for  standard  300 
Plans  and  specifications,  comparative 

importance  of  231 

Problems,  typical  396 

Proposals  380 


411 


INDEX 


Proposals  (continued) 

instructions  to  bidders  381 

typical  385,  388 

additional  work  386 

guaranty  387 

Protective  and  labor  clauses  237 

builders'  insurance  237 

competent  men  and  discharge  for 

cause  237 

employment  of  labor  237 

foreign  corporations  238 

freezing  weather  237 

Purlins  65 


Quantity  estimates 


232 


R 


Rafters  65 

Railroad  grading  249 

Resultant  and  composition  49 

Right  of  way,  delay  in  procuring  233 

Risks  from  floods  240 

Riveted  roof  truss,  design  of  169 

design  of  compression  members     173 

design  of  the  purlins  170 

design  of  tension  members  172 

detail  drawing  181 

estimate  of  cost  185 

top  and  bottom  lateral  bracing      177 

Roads  to  be  opened  241 

Roof  coverings  65,  128 

concrete  slabs  134 

corrugated  steel  132 

felt  and  asphalt  134 

felt  and  gravel  135 

non-condensing  135 

sheathing  129 

sheet  metal  135 

shingles  131 

skylight  glass  130 

slate  129 

tin  130 

Roof  trusses  123-218 

bracing  139 

classes  of  123 

design  of  riveted  roof  truss  169 

Note. — For  page  numbers  see  foot  of  pages. 


Page 
Roof  trusses  (continued) 

details  of  156 

economical  spacing  and  pitch  of  140 
mill  building  186 

physical  analysis  of  125 

rafters  and  purlins  136 

roof  coverings  128 

specifications  for  164 

steel  truss-bent  148 

stresses  in  roof  trusses  142 

suspended  loads  155 

weights  of  65,  128 

wind  pressure  and  snow  loads       126 


8 


240 


Sanitary  regulations 
Sheathing  66 

Snow  loads  66 

analysis  for  84 

Space  diagram  47 

Specification,  spirit  of  245 

Specification   and    contract   writing, 

practice  in  395 

Specifications  224,  249 

concrete  macadam  320 

culverts,  cast-iron  pipes  for  274 

culverts,  terra  cotta  drain  pipes 

for  273 

elevated  tanks  and  standpipes      345 
foundations  256 

highway  bridges  291 

lumber  271 

masonry  256 

overhead    construction    of    an 

electric  railway  313 

pavements  and  curbing  322 

pile  trestle  for  electric  railroad 

across  an  ocean  inlet       296 

railroad  bridges  277 

railroad  grading  249 

stone  road  315 

structural  steel  for  buildings          275 

subaqueous  tunnel,  borings  for      295 

track  laying  305 

tunnels  292 

Sodding  345 

Statics  45-120 


412 


INDEX 


Steel  for  bridges 

erection  290 

inspection  290 

painting  289 

quality  of  285 

shop  work  287 

Stone  road  315 

Stress  diagrams  76 

Stress  records  80 

Structural  steel  for  buildings  275 

estimating  of  11 

basis  of  estimates  13 

degree  of  accuracy  11 

units  11 

variation    from    theoretical 

'     weight  12 

schedule  of  rates  on  37 


Tables 

allowable  unit-stresses,  medium 

steel  167 

analysis  of  cost  of  roof  trusses 

and  mill  buildings  186 

approximate    weights    of    roof 

coverings  129 

bearing  and  shearing  values  of 

rivets  169 

corrugated  steel  data  133 

formulas  giving  weights  of  roof 

trusses  128 

gauges  and  maximum  allowable 

rivets  for  angles  168 

hoist  stresses  in  Fink  truss  147 

maximum  crane  reaction  208 

plate  variations  13 

radii  of  gyration  of  angles  placed 

back  to  back  175 

spacing  of  trusses  141 

stress  record  89,  114 

stress  record  of  truss-bent  under 

wind  load  153 

surface    covered   per   gallon    of 

paint  185 

typical  electric  cranes  209 

unit  weights  of  steel  and  of  cast 

iron  12 

Note. — For  page  numbers  see  foot  of  pages. 


Page 
Tables  (continued) 

wind  pressure  at  various  veloci- 
ties 126 
Tanks  and  standpipes  345 
Time,  extension  of  235 
Time  of  commencement  and  comple- 
tion 238 
Track  laying  305 
ballasting  309 
crossties  310 
handling  supplies  305 
preparing  roadbed  306 
surfacing  310 
Travel,  interference  with  242 
Trusses  65 
apex  loads  66 
Fink  110 
forces  at  a  joint  69 
graphical  analysis  75 
loads  65 
method  of  sections  104 
polygon  for  a  joint  75 
roof  covering  65 
snow  loads  66 
stress  diagrams  76 
stress  in  a  member  69 
stress  records  80 
weight  of  roof  trusses  65 
wind  pressure  66 
Tunnel,  subaqueous,  borings  for  295 
Tunnels  292 

U 
Underground  structures,  location  of    239 


Verbal  agreements 

Verbal  information  to  contractor        228 
Violation  of  laws,  contractor  respon- 
sible for  241 


W 

Weather,  freezing 
Weights,  estimating 

approximate  estimates 

checking 


237 
15 
30 


413 


INDEX 


Weights,  estimating  (continued) 
classification 

beam  work 

riveted  work 
computing  weights 
forms 

listing  material 
standard  material 


Page 

15 
15 
16 
24 
15 
16 
21 


Wind  loads,  analysis  for 
Wind  load  stress 
Wind  pressure 
Work  (general  provisions) 

details  prior  to  beginning 

execution  of 

inspection  of 

obligations  of  contractor 


85 
113 


229 
230 


235 

238 


Note. — For  page  numbers  see  foot  of  pages. 


414 


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